Block vector difference binarization and coding in video coding

ABSTRACT

A method of encoding or decoding video data includes determining that a block vector difference (BVD) value is non-zero, wherein the BVD value is indicative of a difference between a block vector for a current block of the video data and a block vector predictor, and wherein the block vector points to a reference block based on samples in a same picture as the current block; and encoding or decoding a value for the BVD value, without signaling or parsing syntax information indicating whether an absolute value of the BVD value is greater than one.

This application claims the benefit of U.S. Provisional PatentApplication 63/362,782, filed Apr. 11, 2022, the entire content of whichis incorporated by reference.

TECHNICAL FIELD

This disclosure relates to video encoding and video decoding.

BACKGROUND

Digital video capabilities can be incorporated into a wide range ofdevices, including digital televisions, digital direct broadcastsystems, wireless broadcast systems, personal digital assistants (PDAs),laptop or desktop computers, tablet computers, e-book readers, digitalcameras, digital recording devices, digital media players, video gamingdevices, video game consoles, cellular or satellite radio telephones,so-called “smart phones,” video teleconferencing devices, videostreaming devices, and the like. Digital video devices implement videocoding techniques, such as those described in the standards defined byMPEG-2, MPEG-4, ITU-T H.263, ITU-T H.264/MPEG-4, Part 10, Advanced VideoCoding (AVC), ITU-T H.265/High Efficiency Video Coding (HEVC), ITU-TH.266/Versatile Video Coding (VVC), and extensions of such standards, aswell as proprietary video codecs/formats such as AOMedia Video 1 (AV1)that was developed by the Alliance for Open Media. The video devices maytransmit, receive, encode, decode, and/or store digital videoinformation more efficiently by implementing such video codingtechniques.

Video coding techniques include spatial (intra-picture) predictionand/or temporal (inter-picture) prediction to reduce or removeredundancy inherent in video sequences. For block-based video coding, avideo slice (e.g., a video picture or a portion of a video picture) maybe partitioned into video blocks, which may also be referred to ascoding tree units (CTUs), coding units (CUs) and/or coding nodes. Videoblocks in an intra-coded (I) slice of a picture are encoded usingspatial prediction with respect to reference samples in neighboringblocks in the same picture. Video blocks in an inter-coded (P or B)slice of a picture may use spatial prediction with respect to referencesamples in neighboring blocks in the same picture or temporal predictionwith respect to reference samples in other reference pictures. Picturesmay be referred to as frames, and reference pictures may be referred toas reference frames.

SUMMARY

In general, this disclosure describes techniques for coding a blockvector difference (BVD). A BVD may be indicative of a difference betweena block vector (e.g., actual block vector) of a current block and ablock vector predictor. A block vector is a vector for the current blockthat identifies another block in the same picture as the current block.A video encoder may signal the BVD, and a video decoder may receive theBVD. This disclosure describes example techniques of coding the BVD thatmay decrease the amount of information that needs to be signaled and/orreduce the complexity of utilizing BVD as a coding tool.

In one or more examples, a video encoder may signal, and a video decodermay parse syntax information that indicates that a BVD value for a BVDis non-zero. However, the video encoder may not signal, and the videodecoder may not parse additional syntax information that indicateswhether the BVD value is greater than one. Because the video encoderneed not signal, and the video decoder need not parse the additionalsyntax information that indicates whether the BVD value is greater thanone, there may be a reduction in the amount of syntax information thatis signaled.

In one example, the disclosure describes a method of encoding ordecoding video data, the method comprising: determining that a blockvector difference (BVD) value is non-zero, wherein the BVD value isindicative of a difference between a block vector for a current block ofthe video data and a block vector predictor, and wherein the blockvector points to a reference block based on samples in a same picture asthe current block; and encoding or decoding a value for the BVD value,without signaling or parsing syntax information indicating whether anabsolute value of the BVD value is greater than one.

In one example, the disclosure describes a device for encoding ordecoding video data, the device comprising: memory configured to storevideo data; and processing circuitry configured to: determine that ablock vector difference (BVD) value is non-zero, wherein the BVD valueis indicative of a difference between a block vector for a current blockof the video data and a block vector predictor, and wherein the blockvector points to a reference block based on samples in a same picture asthe current block; and encode or decode a value for the BVD value,without signaling or parsing syntax information indicating whether anabsolute value of the BVD value is greater than one.

In one example, the disclosure describes a computer-readable storagemedium storing instructions thereon that when executed cause one or moreprocessors to: determine that a block vector difference (BVD) value isnon-zero, wherein the BVD value is indicative of a difference between ablock vector for a current block of video data and a block vectorpredictor, and wherein the block vector points to a reference blockbased on samples in a same picture as the current block; and encode ordecode a value for the BVD value, without signaling or parsing syntaxinformation indicating whether an absolute value of the BVD value isgreater than one.

The details of one or more examples are set forth in the accompanyingdrawings and the description below. Other features, objects, andadvantages will be apparent from the description, drawings, and claims.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram illustrating an example video encoding anddecoding system that may perform the techniques of this disclosure.

FIG. 2 is a block diagram illustrating an example video encoder that mayperform the techniques of this disclosure.

FIG. 3 is a block diagram illustrating an example video decoder that mayperform the techniques of this disclosure.

FIG. 4 is a flowchart illustrating an example method for encoding acurrent block in accordance with the techniques of this disclosure.

FIG. 5 is a flowchart illustrating an example method for decoding acurrent block in accordance with the techniques of this disclosure.

FIG. 6 is a conceptual diagram illustrating an example of a coding unit(CU) having a matching block identified by a block vector for intrablock copy (IBC).

FIG. 7 is a flowchart illustrating an example method of encoding ordecoding video data in accordance with the techniques of thisdisclosure.

FIG. 8 is a flowchart illustrating an example method of encoding ordecoding components of a block vector difference (BVD).

FIG. 9 is a flowchart illustrating an example method of encoding ordecoding a BVD and a motion vector difference (MVD).

DETAILED DESCRIPTION

Video coding includes an intra-block copy (IBC) video coding tool. InIBC, a video encoder determines a block vector for a current block. Ablock vector identifies another block in the same picture as the currentblock. The video encoder determines a prediction block from the otherblock in the same picture, and determines a residual (e.g., difference)between the current block and the residual block. The video encoder maysignal information indicative of the residual.

In some examples, the video encoder may signal information indicative ofthe block vector. However, to reduce the amount of information that issignaled, rather than signaling information indicative of the blockvector, the video encoder may determine a block vector predictor, and adifference between the block vector and the block vector predictor. Thedifference between the block vector and the block vector predictor isreferred to as the block vector difference (BVD). The video encoder maysignal information indicative of the BVD.

A video decoder may receive the residual information (e.g., differencebetween the current block and the prediction block) and informationindicative of the BVD. The video decoder may determine the BVD from thesignaled information, and determine the block vector predictor using thesame techniques that the video encoder used to determine the blockvector predictor (including based on information signaled by the videoencoder). The video decoder may add the BVD to the block vectorpredictor to reconstruct the block vector for the current block. Fromthe block vector, the video decoder may determine the prediction block.The video decoder may add the prediction block to the residualinformation to reconstruct the current block.

There may be various ways in which the video encoder may signalinformation indicative of the BVD. As one example, the video encoder mayperform a binarization technique to binarize the value of the BVD. Forinstance, the BVD may include a horizontal component and a verticalcomponent, and, in one or more examples, the video encoder may perform abinarization technique to binarize the horizontal and verticalcomponents. The result of the binarization may be a plurality of bins.In one or more examples, the video encoder may context-based encode thevalues of one or more bins representing the horizontal and verticalcomponents.

The video decoder may perform the inverse process as the video encoderto determine the value for the BVD. For instance, the video decoder mayperform context-based decoding to determine the values for the bins ofthe horizontal and vertical components of the BVD to determine thebinarized values of the BVD. The video decoder may perform inversebinarization to determine the values of the BVD.

The binarization and inverse binarization techniques, and thecontext-based encoding and decoding techniques may impact the amount ofinformation that is signaled, and the complexity of the encoding anddecoding process. This disclosure describes example binarization andinverse binarization techniques, and context-based encoding and decodingtechniques that may promote reduction in signaling (e.g., by reducingthe amount of information that needs to be transmitted and received)while balancing complexity to ensure timely decoding of video data.

For instance, this disclosure describes example techniques of reducingthe amount of information that needs to be signaled, relative to othertechniques. As described in more detail, rather than signaling thevalues for the BVD components, a video encoder may signal and a videodecoder may parse flags that indicate whether absolute value of the BVDvalue (e.g., absolute value of one or both of the x and y-components ofthe BVD) is greater than a threshold.

In one or more examples, the video encoder may signal and the videodecoder may parse a first flag that indicates whether the absolute valueof the BVD value is greater than zero (also called gt0 flag). If thegreater than zero flag is true, then the BVD value is non-zero. In oneor more examples, for non-zero BVD values, the video encoder may signal,and the video decoder may parse a value for the BVD value (e.g., thevalue of the BVD value may be equal to the absolute value of the BVDvalue minus one). In such examples, the video encoder may not signal,and the video decoder may not parse syntax information indicatingwhether an absolute value of the BVD value is greater than one.

Some techniques utilize a greater than one flag that indicates whetherthe BVD value is greater than one or not. With the example techniquesdescribed in this disclosure, such a greater than one flag may notneeded, which reduced signaling overhead. Also, signaling smaller valuestends to require less bandwidth compared to larger values. Therefore,the video encoder signaling a value for the BVD value, where the valueis equal to absolute value of the BVD value minus one, results in thevideo encoder signaling a smaller value, which in turn results in lessbandwidth usage.

Moreover, in one or more examples, this disclosure describes examples ofcoding techniques that may provide bandwidth gains. For example, thevalue for the BVD value (e.g., BVD value minus one) may be representedas a codeword (e.g., an Exponential-Golomb codeword). The video encoderand the video decoder may context-based encode or decode the codeword.In some examples, the video encoder and the video decoder maycontext-based encode or decode a first N bins (e.g., 5 bins) of thecodeword, and bypass encode or decode the remaining bins of thecodeword.

For context-based coding, the video encoder and the video decoder mayutilize one or more contexts. In some examples, the video encoder andthe video decoder may utilize a first set of one or more contexts toencode or decode a horizontal component value of the BVD, and utilize asecond set of one or more contexts to encode or decode a verticalcomponent value of the BVD, where the first and second contexts aredifferent. As another example, the contexts used for BVD encoding ordecoding may be different than the contexts used for motion vectordifference (MVD) encoding or decoding. An MVD may be similar to a BVD,but indicative of a difference between a motion vector and motion vectorpredictor, where a motion vector points to samples in a differentpicture. By utilizing different contexts, as described in thisdisclosure, the likelihood of better compression of the horizontaland/or vertical components of the BVD may be increased as compared totechniques that require the same contexts for the horizontal andvertical components of the BVD and/or same contexts for the BVD and MVD.

FIG. 1 is a block diagram illustrating an example video encoding anddecoding system 100 that may perform the techniques of this disclosure.The techniques of this disclosure are generally directed to coding(encoding and/or decoding) video data. In general, video data includesany data for processing a video. Thus, video data may include raw,unencoded video, encoded video, decoded (e.g., reconstructed) video, andvideo metadata, such as signaling data.

As shown in FIG. 1 , system 100 includes a source device 102 thatprovides encoded video data to be decoded and displayed by a destinationdevice 116, in this example. In particular, source device 102 providesthe video data to destination device 116 via a computer-readable medium110. Source device 102 and destination device 116 may comprise any of awide range of devices, including desktop computers, notebook (i.e.,laptop) computers, mobile devices, tablet computers, set-top boxes,telephone handsets such as smartphones, televisions, cameras, displaydevices, digital media players, video gaming consoles, video streamingdevice, broadcast receiver devices, or the like. In some cases, sourcedevice 102 and destination device 116 may be equipped for wirelesscommunication, and thus may be referred to as wireless communicationdevices.

In the example of FIG. 1 , source device 102 includes video source 104,memory 106, video encoder 200, and output interface 108. Destinationdevice 116 includes input interface 122, video decoder 300, memory 120,and display device 118. In accordance with this disclosure, videoencoder 200 of source device 102 and video decoder 300 of destinationdevice 116 may be configured to apply the techniques for block vectordifference (BVD) binarization and coding in video coding. Thus, sourcedevice 102 represents an example of a video encoding device, whiledestination device 116 represents an example of a video decoding device.In other examples, a source device and a destination device may includeother components or arrangements. For example, source device 102 mayreceive video data from an external video source, such as an externalcamera. Likewise, destination device 116 may interface with an externaldisplay device, rather than include an integrated display device.

System 100 as shown in FIG. 1 is merely one example. In general, anydigital video encoding and/or decoding device may perform techniques forBVD binarization and coding. Source device 102 and destination device116 are merely examples of such coding devices in which source device102 generates coded video data for transmission to destination device116. This disclosure refers to a “coding” device as a device thatperforms coding (encoding and/or decoding) of data. Thus, video encoder200 and video decoder 300 represent examples of coding devices, inparticular, a video encoder and a video decoder, respectively. In someexamples, source device 102 and destination device 116 may operate in asubstantially symmetrical manner such that each of source device 102 anddestination device 116 includes video encoding and decoding components.Hence, system 100 may support one-way or two-way video transmissionbetween source device 102 and destination device 116, e.g., for videostreaming, video playback, video broadcasting, or video telephony.

In general, video source 104 represents a source of video data (i.e.,raw, unencoded video data) and provides a sequential series of pictures(also referred to as “frames”) of the video data to video encoder 200,which encodes data for the pictures. Video source 104 of source device102 may include a video capture device, such as a video camera, a videoarchive containing previously captured raw video, and/or a video feedinterface to receive video from a video content provider. As a furtheralternative, video source 104 may generate computer graphics-based dataas the source video, or a combination of live video, archived video, andcomputer-generated video. In each case, video encoder 200 encodes thecaptured, pre-captured, or computer-generated video data. Video encoder200 may rearrange the pictures from the received order (sometimesreferred to as “display order”) into a coding order for coding. Videoencoder 200 may generate a bitstream including encoded video data.Source device 102 may then output the encoded video data via outputinterface 108 onto computer-readable medium 110 for reception and/orretrieval by, e.g., input interface 122 of destination device 116.

Memory 106 of source device 102 and memory 120 of destination device 116represent general purpose memories. In some examples, memories 106, 120may store raw video data, e.g., raw video from video source 104 and raw,decoded video data from video decoder 300. Additionally oralternatively, memories 106, 120 may store software instructionsexecutable by, e.g., video encoder 200 and video decoder 300,respectively. Although memory 106 and memory 120 are shown separatelyfrom video encoder 200 and video decoder 300 in this example, it shouldbe understood that video encoder 200 and video decoder 300 may alsoinclude internal memories for functionally similar or equivalentpurposes. Furthermore, memories 106, 120 may store encoded video data,e.g., output from video encoder 200 and input to video decoder 300. Insome examples, portions of memories 106, 120 may be allocated as one ormore video buffers, e.g., to store raw, decoded, and/or encoded videodata.

Computer-readable medium 110 may represent any type of medium or devicecapable of transporting the encoded video data from source device 102 todestination device 116. In one example, computer-readable medium 110represents a communication medium to enable source device 102 totransmit encoded video data directly to destination device 116 inreal-time, e.g., via a radio frequency network or computer-basednetwork. Output interface 108 may modulate a transmission signalincluding the encoded video data, and input interface 122 may demodulatethe received transmission signal, according to a communication standard,such as a wireless communication protocol. The communication medium maycomprise any wireless or wired communication medium, such as a radiofrequency (RF) spectrum or one or more physical transmission lines. Thecommunication medium may form part of a packet-based network, such as alocal area network, a wide-area network, or a global network such as theInternet. The communication medium may include routers, switches, basestations, or any other equipment that may be useful to facilitatecommunication from source device 102 to destination device 116.

In some examples, source device 102 may output encoded data from outputinterface 108 to storage device 112. Similarly, destination device 116may access encoded data from storage device 112 via input interface 122.Storage device 112 may include any of a variety of distributed orlocally accessed data storage media such as a hard drive, Blu-ray discs,DVDs, CD-ROMs, flash memory, volatile or non-volatile memory, or anyother suitable digital storage media for storing encoded video data.

In some examples, source device 102 may output encoded video data tofile server 114 or another intermediate storage device that may storethe encoded video data generated by source device 102. Destinationdevice 116 may access stored video data from file server 114 viastreaming or download.

File server 114 may be any type of server device capable of storingencoded video data and transmitting that encoded video data to thedestination device 116. File server 114 may represent a web server(e.g., for a website), a server configured to provide a file transferprotocol service (such as File Transfer Protocol (FTP) or File Deliveryover Unidirectional Transport (FLUTE) protocol), a content deliverynetwork (CDN) device, a hypertext transfer protocol (HTTP) server, aMultimedia Broadcast Multicast Service (MBMS) or Enhanced MBMS (eMBMS)server, and/or a network attached storage (NAS) device. File server 114may, additionally or alternatively, implement one or more HTTP streamingprotocols, such as Dynamic Adaptive Streaming over HTTP (DASH), HTTPLive Streaming (HLS), Real Time Streaming Protocol (RTSP), HTTP DynamicStreaming, or the like.

Destination device 116 may access encoded video data from file server114 through any standard data connection, including an Internetconnection. This may include a wireless channel (e.g., a Wi-Ficonnection), a wired connection (e.g., digital subscriber line (DSL),cable modem, etc.), or a combination of both that is suitable foraccessing encoded video data stored on file server 114. Input interface122 may be configured to operate according to any one or more of thevarious protocols discussed above for retrieving or receiving media datafrom file server 114, or other such protocols for retrieving media data.

Output interface 108 and input interface 122 may represent wirelesstransmitters/receivers, modems, wired networking components (e.g.,Ethernet cards), wireless communication components that operateaccording to any of a variety of IEEE 802.11 standards, or otherphysical components. In examples where output interface 108 and inputinterface 122 comprise wireless components, output interface 108 andinput interface 122 may be configured to transfer data, such as encodedvideo data, according to a cellular communication standard, such as 4G,4G-LTE (Long-Term Evolution), LTE Advanced, 5G, or the like. In someexamples where output interface 108 comprises a wireless transmitter,output interface 108 and input interface 122 may be configured totransfer data, such as encoded video data, according to other wirelessstandards, such as an IEEE 802.11 specification, an IEEE 802.15specification (e.g., ZigBee™), a Bluetooth™ standard, or the like. Insome examples, source device 102 and/or destination device 116 mayinclude respective system-on-a-chip (SoC) devices. For example, sourcedevice 102 may include an SoC device to perform the functionalityattributed to video encoder 200 and/or output interface 108, anddestination device 116 may include an SoC device to perform thefunctionality attributed to video decoder 300 and/or input interface122.

The techniques of this disclosure may be applied to video coding insupport of any of a variety of multimedia applications, such asover-the-air television broadcasts, cable television transmissions,satellite television transmissions, Internet streaming videotransmissions, such as dynamic adaptive streaming over HTTP (DASH),digital video that is encoded onto a data storage medium, decoding ofdigital video stored on a data storage medium, or other applications.

Input interface 122 of destination device 116 receives an encoded videobitstream from computer-readable medium 110 (e.g., a communicationmedium, storage device 112, file server 114, or the like). The encodedvideo bitstream may include signaling information defined by videoencoder 200, which is also used by video decoder 300, such as syntaxelements having values that describe characteristics and/or processingof video blocks or other coded units (e.g., slices, pictures, groups ofpictures, sequences, or the like). Display device 118 displays decodedpictures of the decoded video data to a user. Display device 118 mayrepresent any of a variety of display devices such as a liquid crystaldisplay (LCD), a plasma display, an organic light emitting diode (OLED)display, or another type of display device.

Although not shown in FIG. 1 , in some examples, video encoder 200 andvideo decoder 300 may each be integrated with an audio encoder and/oraudio decoder, and may include appropriate MUX-DEMUX units, or otherhardware and/or software, to handle multiplexed streams including bothaudio and video in a common data stream.

Video encoder 200 and video decoder 300 each may be implemented as anyof a variety of suitable encoder and/or decoder circuitry, such as oneor more microprocessors, digital signal processors (DSPs), applicationspecific integrated circuits (ASICs), field programmable gate arrays(FPGAs), discrete logic, software, hardware, firmware or anycombinations thereof. When the techniques are implemented partially insoftware, a device may store instructions for the software in asuitable, non-transitory computer-readable medium and execute theinstructions in hardware using one or more processors to perform thetechniques of this disclosure. Each of video encoder 200 and videodecoder 300 may be included in one or more encoders or decoders, eitherof which may be integrated as part of a combined encoder/decoder (CODEC)in a respective device. A device including video encoder 200 and/orvideo decoder 300 may comprise an integrated circuit, a microprocessor,and/or a wireless communication device, such as a cellular telephone.

Video encoder 200 and video decoder 300 may operate according to a videocoding standard, such as ITU-T H.265, also referred to as HighEfficiency Video Coding (HEVC) or extensions thereto, such as themulti-view and/or scalable video coding extensions. Alternatively, videoencoder 200 and video decoder 300 may operate according to otherproprietary or industry standards, such as ITU-T H.266, also referred toas Versatile Video Coding (VVC). In other examples, video encoder 200and video decoder 300 may operate according to a proprietary videocodec/format, such as AOMedia Video 1 (AV1), extensions of AV1, and/orsuccessor versions of AV1 (e.g., AV2). In other examples, video encoder200 and video decoder 300 may operate according to other proprietaryformats or industry standards. The techniques of this disclosure,however, are not limited to any particular coding standard or format.

In general, video encoder 200 and video decoder 300 may be configured toperform the techniques of this disclosure in conjunction with any videocoding techniques that use intra-block copy (IBC). In IBC, video encoder200 determines a block vector for a current block. A block vectoridentifies another block in the same picture as the current block. Videoencoder 200 determines a prediction block from the other block in thesame picture, and determines a residual (e.g., difference) between thecurrent block and the residual block. Video encoder 200 may signalinformation indicative of the residual.

In some examples, video encoder 200 may signal information indicative ofthe block vector. However, to reduce the amount of information that issignaled, rather than signaling information indicative of the blockvector, video encoder 200 may determine a block vector predictor, and adifference between the block vector and the block vector predictor. Thedifference between the block vector and the block vector predictor isreferred to as the block vector difference (BVD). Video encoder 200 maysignal information indicative of the BVD.

Video decoder 300 may receive the residual information (e.g., differencebetween the current block and the prediction block) and informationindicative of the BVD. Video decoder 300 may determine the BVD from thesignaled information, and determine the block vector predictor using thesame techniques that video encoder 200 used to determine the blockvector predictor (including based on information signaled by videoencoder 200). Video decoder 300 may add the BVD to the block vectorpredictor to reconstruct the block vector for the current block. Fromthe block vector, video decoder 300 may determine the prediction block.Video decoder 300 may add the prediction block to the residualinformation to reconstruct the current block.

In general, video encoder 200 and video decoder 300 may performblock-based coding of pictures. The term “block” generally refers to astructure including data to be processed (e.g., encoded, decoded, orotherwise used in the encoding and/or decoding process). For example, ablock may include a two-dimensional matrix of samples of luminanceand/or chrominance data. In general, video encoder 200 and video decoder300 may code video data represented in a YUV (e.g., Y, Cb, Cr) format.That is, rather than coding red, green, and blue (RGB) data for samplesof a picture, video encoder 200 and video decoder 300 may code luminanceand chrominance components, where the chrominance components may includeboth red hue and blue hue chrominance components. In some examples,video encoder 200 converts received RGB formatted data to a YUVrepresentation prior to encoding, and video decoder 300 converts the YUVrepresentation to the RGB format. Alternatively, pre- andpost-processing units (not shown) may perform these conversions.

This disclosure may generally refer to coding (e.g., encoding anddecoding) of pictures to include the process of encoding or decodingdata of the picture. Similarly, this disclosure may refer to coding ofblocks of a picture to include the process of encoding or decoding datafor the blocks, e.g., prediction and/or residual coding. An encodedvideo bitstream generally includes a series of values for syntaxelements representative of coding decisions (e.g., coding modes) andpartitioning of pictures into blocks. Thus, references to coding apicture or a block should generally be understood as coding values forsyntax elements forming the picture or block.

HEVC defines various blocks, including coding units (CUs), predictionunits (PUs), and transform units (TUs). According to HEVC, a video coder(such as video encoder 200) partitions a coding tree unit (CTU) into CUsaccording to a quadtree structure. That is, the video coder partitionsCTUs and CUs into four equal, non-overlapping squares, and each node ofthe quadtree has either zero or four child nodes. Nodes without childnodes may be referred to as “leaf nodes,” and CUs of such leaf nodes mayinclude one or more PUs and/or one or more TUs. The video coder mayfurther partition PUs and TUs. For example, in HEVC, a residual quadtree(RQT) represents partitioning of TUs. In HEVC, PUs representinter-prediction data, while TUs represent residual data. CUs that areintra-predicted include intra-prediction information, such as anintra-mode indication.

As another example, video encoder 200 and video decoder 300 may beconfigured to operate according to VVC. According to VVC, a video coder(such as video encoder 200) partitions a picture into a plurality ofcoding tree units (CTUs). Video encoder 200 may partition a CTUaccording to a tree structure, such as a quadtree-binary tree (QTBT)structure or Multi-Type Tree (MTT) structure. The QTBT structure removesthe concepts of multiple partition types, such as the separation betweenCUs, PUs, and TUs of HEVC. A QTBT structure includes two levels: a firstlevel partitioned according to quadtree partitioning, and a second levelpartitioned according to binary tree partitioning. A root node of theQTBT structure corresponds to a CTU. Leaf nodes of the binary treescorrespond to coding units (CUs).

In an MTT partitioning structure, blocks may be partitioned using aquadtree (QT) partition, a binary tree (BT) partition, and one or moretypes of triple tree (TT) (also called ternary tree (TT)) partitions. Atriple or ternary tree partition is a partition where a block is splitinto three sub-blocks. In some examples, a triple or ternary treepartition divides a block into three sub-blocks without dividing theoriginal block through the center. The partitioning types in MTT (e.g.,QT, BT, and TT), may be symmetrical or asymmetrical.

When operating according to the AV1 codec, video encoder 200 and videodecoder 300 may be configured to code video data in blocks. In AV1, thelargest coding block that can be processed is called a superblock. InAV1, a superblock can be either 128×128 luma samples or 64×64 lumasamples. However, in successor video coding formats (e.g., AV2), asuperblock may be defined by different (e.g., larger) luma sample sizes.In some examples, a superblock is the top level of a block quadtree.Video encoder 200 may further partition a superblock into smaller codingblocks. Video encoder 200 may partition a superblock and other codingblocks into smaller blocks using square or non-square partitioning.Non-square blocks may include N/2×N, N×N/2, N/4×N, and N×N/4 blocks.Video encoder 200 and video decoder 300 may perform separate predictionand transform processes on each of the coding blocks.

AV1 also defines a tile of video data. A tile is a rectangular array ofsuperblocks that may be coded independently of other tiles. That is,video encoder 200 and video decoder 300 may encode and decode,respectively, coding blocks within a tile without using video data fromother tiles. However, video encoder 200 and video decoder 300 mayperform filtering across tile boundaries. Tiles may be uniform ornon-uniform in size. Tile-based coding may enable parallel processingand/or multi-threading for encoder and decoder implementations.

In some examples, video encoder 200 and video decoder 300 may use asingle QTBT or MTT structure to represent each of the luminance andchrominance components, while in other examples, video encoder 200 andvideo decoder 300 may use two or more QTBT or MTT structures, such asone QTBT/MTT structure for the luminance component and another QTBT/MTTstructure for both chrominance components (or two QTBT/MTT structuresfor respective chrominance components).

Video encoder 200 and video decoder 300 may be configured to usequadtree partitioning, QTBT partitioning, MTT partitioning, superblockpartitioning, or other partitioning structures.

In some examples, a CTU includes a coding tree block (CTB) of lumasamples, two corresponding CTBs of chroma samples of a picture that hasthree sample arrays, or a CTB of samples of a monochrome picture or apicture that is coded using three separate color planes and syntaxstructures used to code the samples. A CTB may be an N×N block ofsamples for some value of N such that the division of a component intoCTBs is a partitioning. A component is an array or single sample fromone of the three arrays (luma and two chroma) that compose a picture in4:2:0, 4:2:2, or 4:4:4 color format or the array or a single sample ofthe array that compose a picture in monochrome format. In some examples,a coding block is an M×N block of samples for some values of M and Nsuch that a division of a CTB into coding blocks is a partitioning.

The blocks (e.g., CTUs or CUs) may be grouped in various ways in apicture. As one example, a brick may refer to a rectangular region ofCTU rows within a particular tile in a picture. A tile may be arectangular region of CTUs within a particular tile column and aparticular tile row in a picture. A tile column refers to a rectangularregion of CTUs having a height equal to the height of the picture and awidth specified by syntax elements (e.g., such as in a picture parameterset). A tile row refers to a rectangular region of CTUs having a heightspecified by syntax elements (e.g., such as in a picture parameter set)and a width equal to the width of the picture.

In some examples, a tile may be partitioned into multiple bricks, eachof which may include one or more CTU rows within the tile. A tile thatis not partitioned into multiple bricks may also be referred to as abrick. However, a brick that is a true subset of a tile may not bereferred to as a tile. The bricks in a picture may also be arranged in aslice. A slice may be an integer number of bricks of a picture that maybe exclusively contained in a single network abstraction layer (NAL)unit. In some examples, a slice includes either a number of completetiles or only a consecutive sequence of complete bricks of one tile.

This disclosure may use “N×N” and “N by N” interchangeably to refer tothe sample dimensions of a block (such as a CU or other video block) interms of vertical and horizontal dimensions, e.g., 16×16 samples or 16by 16 samples. In general, a 16×16 CU will have 16 samples in a verticaldirection (y=16) and 16 samples in a horizontal direction (x=16).Likewise, an N×N CU generally has N samples in a vertical direction andN samples in a horizontal direction, where N represents a nonnegativeinteger value. The samples in a CU may be arranged in rows and columns.Moreover, CUs need not necessarily have the same number of samples inthe horizontal direction as in the vertical direction. For example, CUsmay comprise N×M samples, where M is not necessarily equal to N.

Video encoder 200 encodes video data for CUs representing predictionand/or residual information, and other information. The predictioninformation indicates how the CU is to be predicted in order to form aprediction block for the CU. The residual information generallyrepresents sample-by-sample differences between samples of the CU priorto encoding and the prediction block.

To predict a CU, video encoder 200 may generally form a prediction blockfor the CU through inter-prediction or intra-prediction.Inter-prediction generally refers to predicting the CU from data of apreviously coded picture, whereas intra-prediction generally refers topredicting the CU from previously coded data of the same picture. Toperform inter-prediction, video encoder 200 may generate the predictionblock using one or more motion vectors. Video encoder 200 may generallyperform a motion search to identify a reference block that closelymatches the CU, e.g., in terms of differences between the CU and thereference block. Video encoder 200 may calculate a difference metricusing a sum of absolute difference (SAD), sum of squared differences(SSD), mean absolute difference (MAD), mean squared differences (MSD),or other such difference calculations to determine whether a referenceblock closely matches the current CU. In some examples, video encoder200 may predict the current CU using uni-directional prediction orbi-directional prediction.

Some examples of VVC also provide an affine motion compensation mode,which may be considered an inter-prediction mode. In affine motioncompensation mode, video encoder 200 may determine two or more motionvectors that represent non-translational motion, such as zoom in or out,rotation, perspective motion, or other irregular motion types.

To perform intra-prediction, video encoder 200 may select anintra-prediction mode to generate the prediction block. Some examples ofVVC provide sixty-seven intra-prediction modes, including variousdirectional modes, as well as planar mode and DC mode. In general, videoencoder 200 selects an intra-prediction mode that describes neighboringsamples to a current block (e.g., a block of a CU) from which to predictsamples of the current block. Such samples may generally be above, aboveand to the left, or to the left of the current block in the same pictureas the current block, assuming video encoder 200 codes CTUs and CUs inraster scan order (left to right, top to bottom).

Video encoder 200 encodes data representing the prediction mode for acurrent block. For example, for inter-prediction modes, video encoder200 may encode data representing which of the various availableinter-prediction modes is used, as well as motion information for thecorresponding mode. For uni-directional or bi-directionalinter-prediction, for example, video encoder 200 may encode motionvectors using advanced motion vector prediction (AMVP) or merge mode.Video encoder 200 may use similar modes to encode motion vectors foraffine motion compensation mode.

AV1 includes two general techniques for encoding and decoding a codingblock of video data. The two general techniques are intra prediction(e.g., intra frame prediction or spatial prediction) and interprediction (e.g., inter frame prediction or temporal prediction). In thecontext of AV1, when predicting blocks of a current frame of video datausing an intra prediction mode, video encoder 200 and video decoder 300do not use video data from other frames of video data. For most intraprediction modes, video encoder 200 encodes blocks of a current framebased on the difference between sample values in the current block andpredicted values generated from reference samples in the same frame.Video encoder 200 determines predicted values generated from thereference samples based on the intra prediction mode.

Following prediction, such as intra-prediction or inter-prediction of ablock, video encoder 200 may calculate residual data for the block. Theresidual data, such as a residual block, represents sample by sampledifferences between the block and a prediction block for the block,formed using the corresponding prediction mode. Video encoder 200 mayapply one or more transforms to the residual block, to producetransformed data in a transform domain instead of the sample domain. Forexample, video encoder 200 may apply a discrete cosine transform (DCT),an integer transform, a wavelet transform, or a conceptually similartransform to residual video data. Additionally, video encoder 200 mayapply a secondary transform following the first transform, such as amode-dependent non-separable secondary transform (MDNSST), a signaldependent transform, a Karhunen-Loeve transform (KLT), or the like.Video encoder 200 produces transform coefficients following applicationof the one or more transforms.

As noted above, following any transforms to produce transformcoefficients, video encoder 200 may perform quantization of thetransform coefficients. Quantization generally refers to a process inwhich transform coefficients are quantized to possibly reduce the amountof data used to represent the transform coefficients, providing furthercompression. By performing the quantization process, video encoder 200may reduce the bit depth associated with some or all of the transformcoefficients. For example, video encoder 200 may round an n-bit valuedown to an m-bit value during quantization, where n is greater than m.In some examples, to perform quantization, video encoder 200 may performa bitwise right-shift of the value to be quantized.

Following quantization, video encoder 200 may scan the transformcoefficients, producing a one-dimensional vector from thetwo-dimensional matrix including the quantized transform coefficients.The scan may be designed to place higher energy (and therefore lowerfrequency) transform coefficients at the front of the vector and toplace lower energy (and therefore higher frequency) transformcoefficients at the back of the vector. In some examples, video encoder200 may utilize a predefined scan order to scan the quantized transformcoefficients to produce a serialized vector, and then entropy encode thequantized transform coefficients of the vector. In other examples, videoencoder 200 may perform an adaptive scan. After scanning the quantizedtransform coefficients to form the one-dimensional vector, video encoder200 may entropy encode the one-dimensional vector, e.g., according tocontext-adaptive binary arithmetic coding (CABAC). Video encoder 200 mayalso entropy encode values for syntax elements describing metadataassociated with the encoded video data for use by video decoder 300 indecoding the video data.

To perform CABAC, video encoder 200 may assign a context within acontext model to a symbol to be transmitted. The context may relate to,for example, whether neighboring values of the symbol are zero-valued ornot. The probability determination may be based on a context assigned tothe symbol.

Video encoder 200 may further generate syntax data, such as block-basedsyntax data, picture-based syntax data, and sequence-based syntax data,to video decoder 300, e.g., in a picture header, a block header, a sliceheader, or other syntax data, such as a sequence parameter set (SPS),picture parameter set (PPS), or video parameter set (VPS). Video decoder300 may likewise decode such syntax data to determine how to decodecorresponding video data.

In this manner, video encoder 200 may generate a bitstream includingencoded video data, e.g., syntax elements describing partitioning of apicture into blocks (e.g., CUs) and prediction and/or residualinformation for the blocks. Ultimately, video decoder 300 may receivethe bitstream and decode the encoded video data.

In general, video decoder 300 performs a reciprocal process to thatperformed by video encoder 200 to decode the encoded video data of thebitstream. For example, video decoder 300 may decode values for syntaxelements of the bitstream using CABAC in a manner substantially similarto, albeit reciprocal to, the CABAC encoding process of video encoder200. The syntax elements may define partitioning information forpartitioning of a picture into CTUs, and partitioning of each CTUaccording to a corresponding partition structure, such as a QTBTstructure, to define CUs of the CTU. The syntax elements may furtherdefine prediction and residual information for blocks (e.g., CUs) ofvideo data.

The residual information may be represented by, for example, quantizedtransform coefficients. Video decoder 300 may inverse quantize andinverse transform the quantized transform coefficients of a block toreproduce a residual block for the block. Video decoder 300 uses asignaled prediction mode (intra- or inter-prediction) and relatedprediction information (e.g., motion information for inter-prediction)to form a prediction block for the block. Video decoder 300 may thencombine the prediction block and the residual block (on asample-by-sample basis) to reproduce the original block. Video decoder300 may perform additional processing, such as performing a deblockingprocess to reduce visual artifacts along boundaries of the block.

This disclosure may generally refer to “signaling” certain information,such as syntax elements. The term “signaling” may generally refer to thecommunication of values for syntax elements and/or other data used todecode encoded video data. That is, video encoder 200 may signal valuesfor syntax elements in the bitstream. In general, signaling refers togenerating a value in the bitstream. As noted above, source device 102may transport the bitstream to destination device 116 substantially inreal time, or not in real time, such as might occur when storing syntaxelements to storage device 112 for later retrieval by destination device116.

In accordance with the techniques of this disclosure, video encoder 200and video decoder 300 may be configured to perform the exampletechniques which may improve the coding efficiency and performance ofintra-block copy (IBC) in an enhanced compression model (ECM) beyondVVC. The example techniques may be applicable to the ECM or other videocodecs.

Intra Block Copy (IBC), described in C. Pang, J. Sole, L. Guo, M.Karczewicz, and R. Joshi, “Non-RCE3: Intra Motion Compensation with 2-DMVs”, JCTVC-N0256, Vienna, AT, August 2013, is one of the coding toolsfor screen content. For the current coding unit (CU), IBC will searchall block vectors and find the best matching block in the referenceregion as prediction as shown in FIG. 6 . For instance, FIG. 6illustrates picture 400 that includes CU 402. Block vector 406 of CU 402identifies matching block 404 within the same picture 400.

Video encoder 200 may generate a prediction of the chosen block vector406, referred to as a block vector predictor. Video encoder 200 maydetermine a difference between the chosen block vector 406 and thepredicted block vector (i.e., the block vector predictor). The result ofthe difference is known as a block vector difference (BVD). Videoencoder 200 may signal information indicative of the BVD in thebitstream.

In one or more examples, video encoder 200 may binarize the values forthe BVD (e.g., binarize the values for a horizontal and a verticalcomponent of the BVD) to generate a codeword. Video decoder 300 may beconfigured to perform the inverse binarization (e.g., convert thecodeword back to a value). Fixed length coding is one example techniqueof binarization. A number, which is known to be smaller than two to thepower of N, can be binarized into a binary number of length N. Thenumber is converted to binary first and then 0s are appended to the mostsignificant positions to make the length of binarization to be N.

Table 1 provides examples for fixed-length coding of length 3.

TABLE 1 Example for Fixed-Length Code of length 3 Number Codeword 0 0001 001 2 010 3 011 4 100 5 101 6 110 7 111

Exponential-Golomb coding is also a technique of binarization andexponential-Golomb coding can be generalized to order K.Exponential-Golomb coding may include dividing the whole non-negativenumber set into groups of different numbers for each group.Exponential-Golomb binarization techniques may include converting anon-negative number into the index of the group that the number belongsto and in what position the number is located in the group.Exponential-Golomb coding includes two parts, prefix and suffix. Theprefix is to denote the index of group, and the prefix can be coded withunary coding. The suffix denotes the position inside this group, and iscoded with fixed length coding. Order K indicates that the size of thefirst group should be 2^(K) and the size of the following groups shouldbe 2^(K+1), 2^(K+2),

Table 2 provides examples for Exponential-Golomb coding with order 1.

TABLE 2 Example for Exponential-Golomb Code with order 1 Number GroupPrefix Position in Group Suffix Codeword 0 0 0 0 0 00 1 0 0 1 1 01 2 110 0 00 1000 3 1 10 1 01 1001 4 1 10 2 10 1010 5 1 10 3 11 1011 6 2 1100 000 110000 7 2 110 1 001 110001 8 2 110 2 010 110010 9 2 110 3 011110011 10 2 110 4 100 110100

There may be certain issues with coding BVD. In current ECM software,available at https://vcgit.hhi.fraunhofer.de/ecm/ECM/-/tree/ECM-4.0, thebinarization method for BVD is described as follows. There is onecontext-coded flag signaled to indicate whether the BVD is zero. If thiscontext-coded flag is false, then the BVD value is non-zero. If the BVDvalue is non-zero, there is another context-coded flag signaled toindicate whether the absolute value of the BVD is one (e.g., or greaterthan one). If the absolute value of the BVD is neither zero nor one, twois subtracted from the absolute value and the remaining value of theabsolute BVD is coded with Exponential-Golomb (EG) code of order 1 withequal probability. The sign of the BVD is signaled after with equalprobability.

In some example implantations, the context-coded flags that are used forBVD share the same context with Motion Vector Difference (MVD), and thecoding for the horizontal BVD and the vertical BVD is independent. MVDmay be similar to BVD, except MVD represents a difference between amotion vector and a motion vector predictor. A motion vector for a blockrefers to a block in a different picture, unlike a block vector for ablock that refers to a block in the same picture.

The binarization and coding techniques described above may not providesufficient compression, resulting in inefficient bandwidth utilization.This disclosure describes example binarization and coding techniquesthat may provide additional compression relative to some othertechniques.

Several example techniques are described in this disclosure addressingthe aforementioned issues. The example techniques can be usedindividually or in any combination.

In one example, BVD and MVD use separate contexts. For example, videoencoder 200 and video decoder 300 may code (e.g., encode or decode),utilizing a first set of one or more contexts, a BVD for a block vectorfor a first block in a first picture. The block vector for the firstblock identifies samples in the first picture, and the BVD is indicativeof a difference between the block vector and a block vector predictor.Video encoder 200 and video decoder 300 may code (e.g., encode ordecode), utilizing a second set of one or more contexts, a motion vectordifference (MVD) for a motion vector for a second block in a secondpicture of the video data. The motion vector for the second blockidentifies samples in a picture different than the second picture, andthe MVD is indicative of a difference between the motion vector and amotion vector predictor. In one or more examples, one or more contextsin the first set of contexts and the second set of contexts aredifferent.

In one example, BVD is firstly checked to be zero or not. For instance,as part of rate-distortion calculations, video encoder 200 may determinea BVD value for the BVD, and the BVD value may be non-zero. From theperspective of video decoder 300, video decoder 300 may receive a flagthat indicates that the BVD value is non-zero.

Then EG code is directly applied to BVD without checking whether theabsolute value of BVD is one. For example, a context-coded flag issignaled to indicate whether BVD is zero or not. Then EG code, forexample of order 1, is applied to code the absolute value of BVD minus1.

For example, video encoder 200 or video decoder 300 may determinewhether a block vector difference (BVD) is zero or not, where the BVD isindicative of a difference between a block vector for a current block ofthe video data and a block vector predictor. Video encoder 200 and videodecoder 300 may context-based code (e.g., encode or decode) the BVDbased on the BVD being non-zero, without determining whether an absolutevalue of the BVD is one.

For instance, video encoder 200 may convert a value (e.g., the absolutevalue of the BVD minus one) used to indicate the BVD value into acodeword (e.g., Exponential-Golomb codeword). Video encoder 200 maycontext-based encode the codeword, and signal the resulting encodedcodeword. Video decoder 300 may context-based decode the encodedcodeword to determine the codeword. From the codeword, video decoder 300may (e.g., via inverse-binarization) determine the value used toindicate the BVD value (e.g., the absolute value of the BVD minus one).Video decoder 300 may then add one to the value used to indicate the BVDvalue to determine the BVD value. As described, from the BVD value andthe block vector predictor, video decoder 300 may determine the blockvector (e.g., by adding the BVD value and the block vector predictor).From the block vector, video decoder 300 may determine a predictionblock, and from the prediction block and signaled residual information,video decoder 300 may reconstruct the block.

In one example, after checking if the BVD is zero or not, the absolutevalue of BVD is compared with a threshold. One flag indicating whetherthe absolute value is greater than the threshold or not is signaled. Ifthe absolute value is less or equal to the threshold, one binarizationor inverse binarization technique is applied, otherwise, anotherbinarization or inverse binarization technique is applied. As oneexample, first, whether the BVD is zero or not is checked and a flag issignaled. Then the absolute value of BVD is compared with threshold, forexample 4, if it is less or equal to 4, context-coded flag 0 issignaled, and fix-length coding is applied on the absolute value of BVDminus 1. Otherwise, context-coded flag 1 is signaled and the EG (e.g.,Exponential-Golomb) code, for example with order 3, is applied on theabsolute value of BVD minus threshold.

In one example, first, whether the BVD is zero or not is checked and aflag is signaled. Then the absolute value of BVD is compared withthreshold, for example 6, if it is less or equal to 6, context-codedflag 0 is signaled, and truncated binary coding is applied on theabsolute value of BVD minus 1. Otherwise, context-coded flag 1 issignaled and the EG code, for example with order 4, is applied on theabsolute value of BVD minus threshold.

For example, video encoder 200 or video decoder 300 may determinewhether a block vector difference (BVD) is zero or not, where the BVD isindicative of a difference between a block vector for a current block ofthe video data and a block vector predictor. Based on the BVD beingnon-zero, video encoder 200 and video decoder 300 may determine whetherthe BVD is less than or equal to a threshold (e.g., video encoder 200may compare BVD to threshold, and video decoder 300 may receivesignaling indicative of whether BVD is less than or equal to threshold).Video encoder 200 and video decoder 300 may select a binarization orinverse binarization technique based on whether the BVD is less than orequal to a threshold, and apply the selected binarization or inversebinarization technique.

In one example, contexts can be used in the binarization coding methodof BVD, either for a part of the binarization codeword or for the wholecodeword. In one example, the part of the binarization codeword can bethe first N bins. In another example the context coded part can be aprefix (e.g., prefix part of EG code or prefix part of the concatenatedcodeword). There may be two or more binarization codewords to form theconcatenated codeword, where the prefix is part of the concatenatedcodeword.

For one example, the first 5 bins of EG code, for example with order 1,are context-coded and the remaining codeword is coded with equalprobability, i.e., without context coding. In another example, the first5 bins of the prefix part of EG code, for example with order 1, arecontext-coded and the remaining codeword is coded with equal probability(e.g., bypass coding). In another example, the whole codeword offix-length coding method is context-coded. In another example, the firstN bins, for example 5 bins, of the truncated binary coding method iscontext-coded.

In one or more examples, video encoder 200 and video decoder 300 maycontext-code (e.g., encode or decode), utilizing one or more contexts, ablock vector difference (BVD), where the BVD is indicative of adifference between a block vector for a current block of the video dataand a block vector predictor. The context-coding may include utilizingthe one or more contexts for a part of a binarization codeword of theBVD or for the whole binarization codeword of the BVD.

In one example, the binarization technique for BVD on horizontal andvertical components are different. For example, the binarization methodof horizontal BVD component is as follows. First, check if the BVD isless or equal to a threshold, for example equal to 8. If the BVD is lessor equal to the threshold, fix-length coding is applied, otherwise, EGcode, for example with order 3, is applied. The binarization techniquefor vertical BVD component includes applying EG code, for example withorder 2, directly without checking the threshold.

For example, video encoder 200 and video decoder 300 may be configuredto binarize or inverse binarize a horizontal component of a block vectordifference (BVD) utilizing a first binarization technique, where the BVDis indicative of a difference between a block vector for a current blockof the video data and a block vector predictor. Video encoder 200 andvideo decoder 300 may binarize or inverse binarize a vertical componentof the BVD utilizing a second binarization technique that is differentthan the first binarization technique.

In some examples, video encoder 200 and video decoder 300 may binarizeor inverse binarize a horizontal and vertical component of a blockvector difference (BVD) utilizing the same binarization technique, wherethe BVD is indicative of a difference between a block vector for acurrent block of the video data and a block vector predictor. Videoencoder 200 and video decoder 300 may context-based code (e.g., encodeor decode) the horizontal component, and context-based code thehorizontal component.

In one example, the binarization technique for BVD horizontal andvertical components is the same, and the horizontal and verticalcomponents share the same contexts. For example, context-based codingthe horizontal component and context-based coding the vertical componentmay include context-based coding the vertical component and thehorizontal component utilizing the same contexts.

In one example, the binarization technique for BVD horizontal andvertical components is the same, but the horizontal and verticalcomponents use separate contexts. For example, context-based coding thehorizontal component and context-based coding the vertical component mayinclude context-based coding the vertical component and the horizontalcomponent utilizing different contexts. As an example, video encoder 200may encode or video decoder 300 may decode, utilizing a first set of oneor more contexts, a horizontal component value of the BVD based on theBVD horizontal component value being non-zero, and encode or decode,utilizing a second set of one or more contexts, a vertical componentvalue based on a BVD vertical component value of the BVD being non-zero.The one or more contexts in the first set of contexts and the second setof contexts are different.

In one example, the binarization technique for BVD horizontal andvertical components is the same, but the context of one component isdependent on the other component. For example, context-based coding thehorizontal component and context-based coding the vertical component mayinclude determining contexts for one of the horizontal component or thevertical component based on the other of the horizontal component or thevertical component.

As an example, the context of vertical component is separated for thecases when horizontal BVD is greater than zero, equal to zero, or lessthan zero. In another example, the context of vertical component isseparated for cases when horizontal BVD is zero, or non-zero.

In one example, the binarization method of a BVD component is dependenton the sign of the other BVD component. For example, video encoder 200and video decoder 300 may determine a binarization or inversebinarization technique for a first component of a block vectordifference (BVD) based on whether a second component of the BVD ispositive or negative, where the BVD is indicative of a differencebetween a block vector for a current block of the video data and a blockvector predictor, and where the first component is one of a horizontalor vertical component of the BVD, and the second component is the otherof the horizontal or vertical component of the BVD. Video encoder 200and video decoder 300 may apply the determined binarization or inversebinarization technique.

As an example, the binarization technique of the vertical BVD isdependent on the sign of horizontal BVD component. When the horizontalBVD is positive, the binarization technique for vertical component maybe EG code, for example with order 2. When the horizontal BVD componentis negative, the binarization technique for the vertical component maybe EG code, for example with order 1. When horizontal BVD is zero, thebinarization technique for the vertical component may be fix-lengthcoding.

In one example, the binarization technique of a BVD component may bedependent on the value of the other component. For example, videoencoder 200 and video decoder 300 may determine a binarization orinverse binarization technique for a first component of a block vectordifference (BVD) based on a value of a second component of the BVD,where the BVD is indicative of a difference between a block vector for acurrent block of the video data and a block vector predictor, and wherethe first component is one of a horizontal or vertical component of theBVD, and the second component is the other of the horizontal or verticalcomponent of the BVD. Video encoder 200 and video decoder 300 may applythe determined binarization or inverse binarization technique.

As an example, the binarization technique of vertical BVD is dependenton the magnitude of the horizontal BVD component. When the horizontalBVD is greater than a threshold, for example equal to 8, thebinarization technique of the vertical BVD component is EG code, forexample with order 1. When the BVD for horizontal direction is less thanthe threshold, the binarization technique of the vertical BVD componentmay be fix-length coding.

In one example, BVD binarization technique may depend on the combinationof sign for horizontal and vertical BVD components. For example, videoencoder 200 and video decoder 300 may determine a binarization orinverse binarization technique for a first component of a block vectordifference (BVD) and a second component of the BVD based on whether thefirst component and the second component are both positive, bothnegative, or one is positive and the other is negative, where the BVD isindicative of a difference between a block vector for a current block ofthe video data and a block vector predictor, and where the firstcomponent is one of a horizontal or vertical component of the BVD, andthe second component is the other of the horizontal or verticalcomponent of the BVD. Video encoder 200 and video decoder 300 may applythe determined binarization or inverse binarization technique.

As an example, when the sign combination of horizontal and verticalcomponents is (+, +) and (−, −), EG, for example of order 3, may beutilized. When the sign combination is (+, −), the binarizationtechnique for the horizontal component may be EG code, for example oforder 2, and fix-length coding for the vertical component. When the signcombination is (−, +), the binarization technique of the horizontalcomponent is EG code, for example of order 1, and EG code, for exampleof order 2, for the vertical component.

The examples described above can be used to binarize any vector, forexample to code MVD. BVD vector was used as an example, and thetechniques should not be considered limited to BVD.

FIG. 2 is a block diagram illustrating an example video encoder 200 thatmay perform the techniques of this disclosure. FIG. 2 is provided forpurposes of explanation and should not be considered limiting of thetechniques as broadly exemplified and described in this disclosure. Forpurposes of explanation, this disclosure describes video encoder 200according to the techniques of VVC (ITU-T H.266, under development), andHEVC (ITU-T H.265). However, the techniques of this disclosure may beperformed by video encoding devices that are configured to other videocoding standards and video coding formats, such as AV1 and successors tothe AV1 video coding format.

In the example of FIG. 2 , video encoder 200 includes video data memory230, mode selection unit 202, residual generation unit 204, transformprocessing unit 206, quantization unit 208, inverse quantization unit210, inverse transform processing unit 212, reconstruction unit 214,filter unit 216, decoded picture buffer (DPB) 218, and entropy encodingunit 220. Any or all of video data memory 230, mode selection unit 202,residual generation unit 204, transform processing unit 206,quantization unit 208, inverse quantization unit 210, inverse transformprocessing unit 212, reconstruction unit 214, filter unit 216, DPB 218,and entropy encoding unit 220 may be implemented in one or moreprocessors or in processing circuitry. For instance, the units of videoencoder 200 may be implemented as one or more circuits or logic elementsas part of hardware circuitry, or as part of a processor, ASIC, or FPGA.Moreover, video encoder 200 may include additional or alternativeprocessors or processing circuitry to perform these and other functions.

Video data memory 230 may store video data to be encoded by thecomponents of video encoder 200. Video encoder 200 may receive the videodata stored in video data memory 230 from, for example, video source 104(FIG. 1 ). DPB 218 may act as a reference picture memory that storesreference video data for use in prediction of subsequent video data byvideo encoder 200. Video data memory 230 and DPB 218 may be formed byany of a variety of memory devices, such as dynamic random access memory(DRAM), including synchronous DRAM (SDRAM), magnetoresistive RAM (MRAM),resistive RAM (RRAM), or other types of memory devices. Video datamemory 230 and DPB 218 may be provided by the same memory device orseparate memory devices. In various examples, video data memory 230 maybe on-chip with other components of video encoder 200, as illustrated,or off-chip relative to those components.

In this disclosure, reference to video data memory 230 should not beinterpreted as being limited to memory internal to video encoder 200,unless specifically described as such, or memory external to videoencoder 200, unless specifically described as such. Rather, reference tovideo data memory 230 should be understood as reference memory thatstores video data that video encoder 200 receives for encoding (e.g.,video data for a current block that is to be encoded). Memory 106 ofFIG. 1 may also provide temporary storage of outputs from the variousunits of video encoder 200.

The various units of FIG. 2 are illustrated to assist with understandingthe operations performed by video encoder 200. The units may beimplemented as fixed-function circuits, programmable circuits, or acombination thereof. Fixed-function circuits refer to circuits thatprovide particular functionality, and are preset on the operations thatcan be performed. Programmable circuits refer to circuits that can beprogrammed to perform various tasks, and provide flexible functionalityin the operations that can be performed. For instance, programmablecircuits may execute software or firmware that cause the programmablecircuits to operate in the manner defined by instructions of thesoftware or firmware. Fixed-function circuits may execute softwareinstructions (e.g., to receive parameters or output parameters), but thetypes of operations that the fixed-function circuits perform aregenerally immutable. In some examples, one or more of the units may bedistinct circuit blocks (fixed-function or programmable), and in someexamples, one or more of the units may be integrated circuits.

Video encoder 200 may include arithmetic logic units (ALUs), elementaryfunction units (EFUs), digital circuits, analog circuits, and/orprogrammable cores, formed from programmable circuits. In examples wherethe operations of video encoder 200 are performed using softwareexecuted by the programmable circuits, memory 106 (FIG. 1 ) may storethe instructions (e.g., object code) of the software that video encoder200 receives and executes, or another memory within video encoder 200(not shown) may store such instructions.

Video data memory 230 is configured to store received video data. Videoencoder 200 may retrieve a picture of the video data from video datamemory 230 and provide the video data to residual generation unit 204and mode selection unit 202. Video data in video data memory 230 may beraw video data that is to be encoded.

Mode selection unit 202 includes a motion estimation unit 222, a motioncompensation unit 224, and an intra-prediction unit 226. Mode selectionunit 202 may include additional functional units to perform videoprediction in accordance with other prediction modes. As examples, modeselection unit 202 may include a palette unit, intra-block copy (IBC)unit 227, an affine unit, a linear model (LM) unit, or the like. In someexamples, IBC unit 227 may be part of motion estimation unit 222 and/ormotion compensation unit 224.

Mode selection unit 202 generally coordinates multiple encoding passesto test combinations of encoding parameters and resultingrate-distortion values for such combinations. The encoding parametersmay include partitioning of CTUs into CUs, prediction modes for the CUs,transform types for residual data of the CUs, quantization parametersfor residual data of the CUs, and so on. Mode selection unit 202 mayultimately select the combination of encoding parameters havingrate-distortion values that are better than the other testedcombinations.

Video encoder 200 may partition a picture retrieved from video datamemory 230 into a series of CTUs, and encapsulate one or more CTUswithin a slice. Mode selection unit 202 may partition a CTU of thepicture in accordance with a tree structure, such as the MTT structure,QTBT structure. superblock structure, or the quad-tree structuredescribed above. As described above, video encoder 200 may form one ormore CUs from partitioning a CTU according to the tree structure. Such aCU may also be referred to generally as a “video block” or “block.”

In general, mode selection unit 202 also controls the components thereof(e.g., motion estimation unit 222, motion compensation unit 224, andintra-prediction unit 226) to generate a prediction block for a currentblock (e.g., a current CU, or in HEVC, the overlapping portion of a PUand a TU). For inter-prediction of a current block, motion estimationunit 222 may perform a motion search to identify one or more closelymatching reference blocks in one or more reference pictures (e.g., oneor more previously coded pictures stored in DPB 218). In particular,motion estimation unit 222 may calculate a value representative of howsimilar a potential reference block is to the current block, e.g.,according to sum of absolute difference (SAD), sum of squareddifferences (SSD), mean absolute difference (MAD), mean squareddifferences (MSD), or the like. Motion estimation unit 222 may generallyperform these calculations using sample-by-sample differences betweenthe current block and the reference block being considered. Motionestimation unit 222 may identify a reference block having a lowest valueresulting from these calculations, indicating a reference block thatmost closely matches the current block.

Motion estimation unit 222 may form one or more motion vectors (MVs)that defines the positions of the reference blocks in the referencepictures relative to the position of the current block in a currentpicture. Motion estimation unit 222 may then provide the motion vectorsto motion compensation unit 224. For example, for uni-directionalinter-prediction, motion estimation unit 222 may provide a single motionvector, whereas for bi-directional inter-prediction, motion estimationunit 222 may provide two motion vectors. Motion compensation unit 224may then generate a prediction block using the motion vectors. Forexample, motion compensation unit 224 may retrieve data of the referenceblock using the motion vector. As another example, if the motion vectorhas fractional sample precision, motion compensation unit 224 mayinterpolate values for the prediction block according to one or moreinterpolation filters. Moreover, for bi-directional inter-prediction,motion compensation unit 224 may retrieve data for two reference blocksidentified by respective motion vectors and combine the retrieved data,e.g., through sample-by-sample averaging or weighted averaging.

When operating according to the AV1 video coding format, motionestimation unit 222 and motion compensation unit 224 may be configuredto encode coding blocks of video data (e.g., both luma and chroma codingblocks) using translational motion compensation, affine motioncompensation, overlapped block motion compensation (OBMC), and/orcompound inter-intra prediction.

As another example, for intra-prediction, or intra-prediction coding,intra-prediction unit 226 may generate the prediction block from samplesneighboring the current block. For example, for directional modes,intra-prediction unit 226 may generally mathematically combine values ofneighboring samples and populate these calculated values in the defineddirection across the current block to produce the prediction block. Asanother example, for DC mode, intra-prediction unit 226 may calculate anaverage of the neighboring samples to the current block and generate theprediction block to include this resulting average for each sample ofthe prediction block.

When operating according to the AV1 video coding format, intraprediction unit 226 may be configured to encode coding blocks of videodata (e.g., both luma and chroma coding blocks) using directional intraprediction, non-directional intra prediction, recursive filter intraprediction, chroma-from-luma (CFL) prediction, intra block copy (IBC),and/or color palette mode. Mode selection unit 202 may includeadditional functional units to perform video prediction in accordancewith other prediction modes.

As described above, the example techniques described in this disclosureare related to intra-block copy (IBC). Mode selection unit 202 mayinclude IBC unit 227. IBC unit 227 may be configured to determine ablock vector for a current block, and generate a prediction block forthe current block based on the block vector. For instance, the blockvector may identify a block within the same picture as the currentblock, and IBC unit 227 may determine the prediction block based on thesamples within the block identified by the block vector. In one or moreexamples, IBC unit 227 may be configured to determine a block vectorpredictor for the block vector, and a BVD (e.g., difference betweenblock vector and block vector predictor).

Mode selection unit 202 provides the prediction block to residualgeneration unit 204. Residual generation unit 204 receives a raw,unencoded version of the current block from video data memory 230 andthe prediction block from mode selection unit 202. Residual generationunit 204 calculates sample-by-sample differences between the currentblock and the prediction block. The resulting sample-by-sampledifferences define a residual block for the current block. In someexamples, residual generation unit 204 may also determine differencesbetween sample values in the residual block to generate a residual blockusing residual differential pulse code modulation (RDPCM). In someexamples, residual generation unit 204 may be formed using one or moresubtractor circuits that perform binary subtraction.

In examples where mode selection unit 202 partitions CUs into PUs, eachPU may be associated with a luma prediction unit and correspondingchroma prediction units. Video encoder 200 and video decoder 300 maysupport PUs having various sizes. As indicated above, the size of a CUmay refer to the size of the luma coding block of the CU and the size ofa PU may refer to the size of a luma prediction unit of the PU. Assumingthat the size of a particular CU is 2N×2N, video encoder 200 may supportPU sizes of 2N×2N or N×N for intra prediction, and symmetric PU sizes of2N×2N, 2N×N, N×2N, N×N, or similar for inter prediction. Video encoder200 and video decoder 300 may also support asymmetric partitioning forPU sizes of 2N×nU, 2N×nD, nL×2N, and nR×2N for inter prediction.

In examples where mode selection unit 202 does not further partition aCU into PUs, each CU may be associated with a luma coding block andcorresponding chroma coding blocks. As above, the size of a CU may referto the size of the luma coding block of the CU. The video encoder 200and video decoder 300 may support CU sizes of 2N×2N, 2N×N, or N×2N.

For other video coding techniques such as an affine-mode coding andlinear model (LM) mode coding, as some examples, mode selection unit202, via respective units associated with the coding techniques,generates a prediction block for the current block being encoded. Insome examples, such as palette mode coding, mode selection unit 202 maynot generate a prediction block, and instead generate syntax elementsthat indicate the manner in which to reconstruct the block based on aselected palette. In such modes, mode selection unit 202 may providethese syntax elements to entropy encoding unit 220 to be encoded.

As described above, residual generation unit 204 receives the video datafor the current block and the corresponding prediction block. Residualgeneration unit 204 then generates a residual block for the currentblock. To generate the residual block, residual generation unit 204calculates sample-by-sample differences between the prediction block andthe current block.

Transform processing unit 206 applies one or more transforms to theresidual block to generate a block of transform coefficients (referredto herein as a “transform coefficient block”). Transform processing unit206 may apply various transforms to a residual block to form thetransform coefficient block. For example, transform processing unit 206may apply a discrete cosine transform (DCT), a directional transform, aKarhunen-Loeve transform (KLT), or a conceptually similar transform to aresidual block. In some examples, transform processing unit 206 mayperform multiple transforms to a residual block, e.g., a primarytransform and a secondary transform, such as a rotational transform. Insome examples, transform processing unit 206 does not apply transformsto a residual block.

When operating according to AV1, transform processing unit 206 may applyone or more transforms to the residual block to generate a block oftransform coefficients (referred to herein as a “transform coefficientblock”). Transform processing unit 206 may apply various transforms to aresidual block to form the transform coefficient block. For example,transform processing unit 206 may apply a horizontal/vertical transformcombination that may include a discrete cosine transform (DCT), anasymmetric discrete sine transform (ADST), a flipped ADST (e.g., an ADSTin reverse order), and an identity transform (IDTX). When using anidentity transform, the transform is skipped in one of the vertical orhorizontal directions. In some examples, transform processing may beskipped.

Quantization unit 208 may quantize the transform coefficients in atransform coefficient block, to produce a quantized transformcoefficient block. Quantization unit 208 may quantize transformcoefficients of a transform coefficient block according to aquantization parameter (QP) value associated with the current block.Video encoder 200 (e.g., via mode selection unit 202) may adjust thedegree of quantization applied to the transform coefficient blocksassociated with the current block by adjusting the QP value associatedwith the CU. Quantization may introduce loss of information, and thus,quantized transform coefficients may have lower precision than theoriginal transform coefficients produced by transform processing unit206.

Inverse quantization unit 210 and inverse transform processing unit 212may apply inverse quantization and inverse transforms to a quantizedtransform coefficient block, respectively, to reconstruct a residualblock from the transform coefficient block. Reconstruction unit 214 mayproduce a reconstructed block corresponding to the current block (albeitpotentially with some degree of distortion) based on the reconstructedresidual block and a prediction block generated by mode selection unit202. For example, reconstruction unit 214 may add samples of thereconstructed residual block to corresponding samples from theprediction block generated by mode selection unit 202 to produce thereconstructed block.

Filter unit 216 may perform one or more filter operations onreconstructed blocks. For example, filter unit 216 may performdeblocking operations to reduce blockiness artifacts along edges of CUs.Operations of filter unit 216 may be skipped, in some examples.

When operating according to AV1, filter unit 216 may perform one or morefilter operations on reconstructed blocks. For example, filter unit 216may perform deblocking operations to reduce blockiness artifacts alongedges of CUs. In other examples, filter unit 216 may apply a constraineddirectional enhancement filter (CDEF), which may be applied afterdeblocking, and may include the application of non-separable,non-linear, low-pass directional filters based on estimated edgedirections. Filter unit 216 may also include a loop restoration filter,which is applied after CDEF, and may include a separable symmetricnormalized Wiener filter or a dual self-guided filter.

Video encoder 200 stores reconstructed blocks in DPB 218. For instance,in examples where operations of filter unit 216 are not performed,reconstruction unit 214 may store reconstructed blocks to DPB 218. Inexamples where operations of filter unit 216 are performed, filter unit216 may store the filtered reconstructed blocks to DPB 218. Motionestimation unit 222 and motion compensation unit 224 may retrieve areference picture from DPB 218, formed from the reconstructed (andpotentially filtered) blocks, to inter-predict blocks of subsequentlyencoded pictures. In addition, intra-prediction unit 226 may usereconstructed blocks in DPB 218 of a current picture to intra-predictother blocks in the current picture.

In general, entropy encoding unit 220 may entropy encode syntax elementsreceived from other functional components of video encoder 200. Forexample, entropy encoding unit 220 may entropy encode quantizedtransform coefficient blocks from quantization unit 208. As anotherexample, entropy encoding unit 220 may entropy encode prediction syntaxelements (e.g., motion information for inter-prediction or intra-modeinformation for intra-prediction) from mode selection unit 202. Entropyencoding unit 220 may perform one or more entropy encoding operations onthe syntax elements, which are another example of video data, togenerate entropy-encoded data. For example, entropy encoding unit 220may perform a context-adaptive variable length coding (CAVLC) operation,a CABAC operation, a variable-to-variable (V2V) length coding operation,a syntax-based context-adaptive binary arithmetic coding (SBAC)operation, a Probability Interval Partitioning Entropy (PIPE) codingoperation, an Exponential-Golomb encoding operation, or another type ofentropy encoding operation on the data. In some examples, entropyencoding unit 220 may operate in bypass mode where syntax elements arenot entropy encoded.

Video encoder 200 may output a bitstream that includes the entropyencoded syntax elements needed to reconstruct blocks of a slice orpicture. In particular, entropy encoding unit 220 may output thebitstream.

In accordance with AV1, entropy encoding unit 220 may be configured as asymbol-to-symbol adaptive multi-symbol arithmetic coder. A syntaxelement in AV1 includes an alphabet of N elements, and a context (e.g.,probability model) includes a set of N probabilities. Entropy encodingunit 220 may store the probabilities as n-bit (e.g., 15-bit) cumulativedistribution functions (CDFs). Entropy encoding unit 22 may performrecursive scaling, with an update factor based on the alphabet size, toupdate the contexts.

The operations described above are described with respect to a block.Such description should be understood as being operations for a lumacoding block and/or chroma coding blocks. As described above, in someexamples, the luma coding block and chroma coding blocks are luma andchroma components of a CU. In some examples, the luma coding block andthe chroma coding blocks are luma and chroma components of a PU.

In some examples, operations performed with respect to a luma codingblock need not be repeated for the chroma coding blocks. As one example,operations to identify a motion vector (MV) and reference picture for aluma coding block need not be repeated for identifying a MV andreference picture for the chroma blocks. Rather, the MV for the lumacoding block may be scaled to determine the MV for the chroma blocks,and the reference picture may be the same. As another example, theintra-prediction process may be the same for the luma coding block andthe chroma coding blocks.

Video encoder 200 represents an example of a device configured to encodevideo data including a memory configured to store video data, and one ormore processing units implemented in circuitry and configured to performthe example techniques described in this disclosure, such as the varioustechniques for binarizing and encoding information indicative of theBVD.

For example, IBC unit 227 may determine that a block vector difference(BVD) value is non-zero. The BVD value is indicative of a differencebetween a block vector for a current block of the video data and a blockvector predictor, and the block vector points to a reference block basedon samples in a same picture as the current block. Entropy encoding unit220 may encode a value for the BVD value, without signaling syntaxinformation indicating whether an absolute value of the BVD value isgreater than one.

As one example, a value, for the BVD value, is equal to the absolutevalue of the BVD value minus one. Entropy encoding unit 220 may encodethe value that is equal to the absolute value of the BVD value minusone. In some examples, entropy encoding unit 220 may performbinarization (e.g., Exponential-Golomb) to represent the value as acodeword and encode the codeword. For example, entropy encoding unit 220may context-based encode the codeword (e.g., a first N bins of thecodeword and bypass encode the remaining bins of the codeword).

In some examples, entropy encoding unit 220 may utilize differentcontexts for encoding horizontal and vertical components of the BVD. Forexample, entropy encoding unit 220 may encode, utilizing a first set ofone or more contexts, the horizontal component value based on the BVDhorizontal component value being non-zero, and encode, utilizing asecond set of one or more contexts, a vertical component value based ona BVD vertical component value being non-zero. The one or more contextsin the first set of contexts and the second set of contexts aredifferent.

As another example, entropy encoding unit 220 may encode, utilizing afirst set of one or more contexts, the value for the BVD value for afirst block in a first picture, and encode, utilizing a second set ofone or more contexts, a motion vector difference (MVD) for a motionvector for a second block in a second picture. The motion vector for thesecond block identifies a block in a picture different than the secondpicture, and the MVD is indicative of a difference between the motionvector and a motion vector predictor. In one or more examples, one ormore contexts in the first set of contexts and the second set ofcontexts are different.

FIG. 3 is a block diagram illustrating an example video decoder 300 thatmay perform the techniques of this disclosure. FIG. 3 is provided forpurposes of explanation and is not limiting on the techniques as broadlyexemplified and described in this disclosure. For purposes ofexplanation, this disclosure describes video decoder 300 according tothe techniques of VVC (ITU-T H.266, under development), and HEVC (ITU-TH.265). However, the techniques of this disclosure may be performed byvideo coding devices that are configured to other video codingstandards.

In the example of FIG. 3 , video decoder 300 includes coded picturebuffer (CPB) memory 320, entropy decoding unit 302, predictionprocessing unit 304, inverse quantization unit 306, inverse transformprocessing unit 308, reconstruction unit 310, filter unit 312, anddecoded picture buffer (DPB) 314. Any or all of CPB memory 320, entropydecoding unit 302, prediction processing unit 304, inverse quantizationunit 306, inverse transform processing unit 308, reconstruction unit310, filter unit 312, and DPB 314 may be implemented in one or moreprocessors or in processing circuitry. For instance, the units of videodecoder 300 may be implemented as one or more circuits or logic elementsas part of hardware circuitry, or as part of a processor, ASIC, or FPGA.Moreover, video decoder 300 may include additional or alternativeprocessors or processing circuitry to perform these and other functions.

Prediction processing unit 304 includes motion compensation unit 316,intra-block copy (IBC) unit 317, and intra-prediction unit 318. In someexamples, IBC unit 317 may be part of motion compensation unit 316.Prediction processing unit 304 may include additional units to performprediction in accordance with other prediction modes. As examples,prediction processing unit 304 may include a palette unit, an affineunit, a linear model (LM) unit, or the like. In other examples, videodecoder 300 may include more, fewer, or different functional components.

As described above, the example techniques described in this disclosureare related to intra-block copy (IBC). IBC unit 317 may be configured todetermine a block vector for a current block, and generate a predictionblock for the current block based on the block vector. For instance, theblock vector may identify a block within the same picture as the currentblock, and IBC unit 317 may determine the prediction block based on thesamples within the block identified by the block vector. In one or moreexamples, IBC unit 317 may be configured to determine a block vectorpredictor for the block vector, and receive information indicative of aBVD (e.g., difference between block vector and block vector predictor).IBC unit 317 may add the BVD to the block vector predictor to generatethe block vector for the current block, and determine the predictionblock for the current block based on the block vector.

When operating according to AV1, motion compensation unit 316 may beconfigured to decode coding blocks of video data (e.g., both luma andchroma coding blocks) using translational motion compensation, affinemotion compensation, OBMC, and/or compound inter-intra prediction, asdescribed above. Intra prediction unit 318 may be configured to decodecoding blocks of video data (e.g., both luma and chroma coding blocks)using directional intra prediction, non-directional intra prediction,recursive filter intra prediction, CFL, intra block copy (IBC), and/orcolor palette mode, as described above.

CPB memory 320 may store video data, such as an encoded video bitstream,to be decoded by the components of video decoder 300. The video datastored in CPB memory 320 may be obtained, for example, fromcomputer-readable medium 110 (FIG. 1 ). CPB memory 320 may include a CPBthat stores encoded video data (e.g., syntax elements) from an encodedvideo bitstream. Also, CPB memory 320 may store video data other thansyntax elements of a coded picture, such as temporary data representingoutputs from the various units of video decoder 300. DPB 314 generallystores decoded pictures, which video decoder 300 may output and/or useas reference video data when decoding subsequent data or pictures of theencoded video bitstream. CPB memory 320 and DPB 314 may be formed by anyof a variety of memory devices, such as DRAM, including SDRAM, MRAM,RRAM, or other types of memory devices. CPB memory 320 and DPB 314 maybe provided by the same memory device or separate memory devices. Invarious examples, CPB memory 320 may be on-chip with other components ofvideo decoder 300, or off-chip relative to those components.

Additionally or alternatively, in some examples, video decoder 300 mayretrieve coded video data from memory 120 (FIG. 1 ). That is, memory 120may store data as discussed above with CPB memory 320. Likewise, memory120 may store instructions to be executed by video decoder 300, whensome or all of the functionality of video decoder 300 is implemented insoftware to be executed by processing circuitry of video decoder 300.

The various units shown in FIG. 3 are illustrated to assist withunderstanding the operations performed by video decoder 300. The unitsmay be implemented as fixed-function circuits, programmable circuits, ora combination thereof. Similar to FIG. 2 , fixed-function circuits referto circuits that provide particular functionality, and are preset on theoperations that can be performed. Programmable circuits refer tocircuits that can be programmed to perform various tasks, and provideflexible functionality in the operations that can be performed. Forinstance, programmable circuits may execute software or firmware thatcause the programmable circuits to operate in the manner defined byinstructions of the software or firmware. Fixed-function circuits mayexecute software instructions (e.g., to receive parameters or outputparameters), but the types of operations that the fixed-functioncircuits perform are generally immutable. In some examples, one or moreof the units may be distinct circuit blocks (fixed-function orprogrammable), and in some examples, one or more of the units may beintegrated circuits.

Video decoder 300 may include ALUs, EFUs, digital circuits, analogcircuits, and/or programmable cores formed from programmable circuits.In examples where the operations of video decoder 300 are performed bysoftware executing on the programmable circuits, on-chip or off-chipmemory may store instructions (e.g., object code) of the software thatvideo decoder 300 receives and executes.

Entropy decoding unit 302 may receive encoded video data from the CPBand entropy decode the video data to reproduce syntax elements.Prediction processing unit 304, inverse quantization unit 306, inversetransform processing unit 308, reconstruction unit 310, and filter unit312 may generate decoded video data based on the syntax elementsextracted from the bitstream.

In general, video decoder 300 reconstructs a picture on a block-by-blockbasis. Video decoder 300 may perform a reconstruction operation on eachblock individually (where the block currently being reconstructed, i.e.,decoded, may be referred to as a “current block”).

Entropy decoding unit 302 may entropy decode syntax elements definingquantized transform coefficients of a quantized transform coefficientblock, as well as transform information, such as a quantizationparameter (QP) and/or transform mode indication(s). Inverse quantizationunit 306 may use the QP associated with the quantized transformcoefficient block to determine a degree of quantization and, likewise, adegree of inverse quantization for inverse quantization unit 306 toapply. Inverse quantization unit 306 may, for example, perform a bitwiseleft-shift operation to inverse quantize the quantized transformcoefficients. Inverse quantization unit 306 may thereby form a transformcoefficient block including transform coefficients.

After inverse quantization unit 306 forms the transform coefficientblock, inverse transform processing unit 308 may apply one or moreinverse transforms to the transform coefficient block to generate aresidual block associated with the current block. For example, inversetransform processing unit 308 may apply an inverse DCT, an inverseinteger transform, an inverse Karhunen-Loeve transform (KLT), an inverserotational transform, an inverse directional transform, or anotherinverse transform to the transform coefficient block.

Furthermore, prediction processing unit 304 generates a prediction blockaccording to prediction information syntax elements that were entropydecoded by entropy decoding unit 302. For example, if the predictioninformation syntax elements indicate that the current block isinter-predicted, motion compensation unit 316 may generate theprediction block. In this case, the prediction information syntaxelements may indicate a reference picture in DPB 314 from which toretrieve a reference block, as well as a motion vector identifying alocation of the reference block in the reference picture relative to thelocation of the current block in the current picture. Motioncompensation unit 316 may generally perform the inter-prediction processin a manner that is substantially similar to that described with respectto motion compensation unit 224 (FIG. 2 ).

As another example, if the prediction information syntax elementsindicate that the current block is intra-predicted, intra-predictionunit 318 may generate the prediction block according to anintra-prediction mode indicated by the prediction information syntaxelements. Again, intra-prediction unit 318 may generally perform theintra-prediction process in a manner that is substantially similar tothat described with respect to intra-prediction unit 226 (FIG. 2 ).Intra-prediction unit 318 may retrieve data of neighboring samples tothe current block from DPB 314.

Reconstruction unit 310 may reconstruct the current block using theprediction block and the residual block. For example, reconstructionunit 310 may add samples of the residual block to corresponding samplesof the prediction block to reconstruct the current block.

Filter unit 312 may perform one or more filter operations onreconstructed blocks. For example, filter unit 312 may performdeblocking operations to reduce blockiness artifacts along edges of thereconstructed blocks. Operations of filter unit 312 are not necessarilyperformed in all examples.

Video decoder 300 may store the reconstructed blocks in DPB 314. Forinstance, in examples where operations of filter unit 312 are notperformed, reconstruction unit 310 may store reconstructed blocks to DPB314. In examples where operations of filter unit 312 are performed,filter unit 312 may store the filtered reconstructed blocks to DPB 314.As discussed above, DPB 314 may provide reference information, such assamples of a current picture for intra-prediction and previously decodedpictures for subsequent motion compensation, to prediction processingunit 304. Moreover, video decoder 300 may output decoded pictures (e.g.,decoded video) from DPB 314 for subsequent presentation on a displaydevice, such as display device 118 of FIG. 1 .

In this manner, video decoder 300 represents an example of a videodecoding device including a memory configured to store video data, andone or more processing units implemented in circuitry and configured toperform the example techniques described in this disclosure, such as thevarious techniques for inverse binarizing and decoding informationindicative of the BVD.

For example, IBC unit 317 may determine that a block vector difference(BVD) value is non-zero. The BVD value is indicative of a differencebetween a block vector for a current block of the video data and a blockvector predictor, and the block vector points to a reference block basedon samples in a same picture as the current block. Entropy decoding unit302 may decode a value for the BVD value, without parsing syntaxinformation indicating whether an absolute value of the BVD value isgreater than one.

As one example, a value, for the BVD value, is equal to the absolutevalue of the BVD value minus one. Entropy decoding unit 302 may decodethe value that is equal to the absolute value of the BVD value minusone. IBC unit 317 may add one to the value to determine the BVD value.From the BVD value, IBC unit 317 may determine the block vector (e.g.,by adding the BVD value to the block vector predictor that video encoder200 signaled). From the block vector, IBC unit 317 may determine aprediction block that IBC unit 317 outputs to reconstruction unit 310 toreconstruct the current block.

In some examples, entropy decoding unit 302 may performinverse-binarization (e.g., Exponential-Golomb), such as in exampleswhere the value is represented as a codeword and decode the codeword.For example, entropy decoding unit 302 may context-based decode thecodeword (e.g., a first N bins of the codeword and bypass decode theremaining bins of the codeword).

In some examples, entropy decoding unit 302 may utilize differentcontexts for decoding horizontal and vertical components of the BVD. Forexample, entropy decoding unit 302 may decode, utilizing a first set ofone or more contexts, the horizontal component value based on the BVDhorizontal component value being non-zero, and decode, utilizing asecond set of one or more contexts, a vertical component value based ona BVD vertical component value being non-zero. The one or more contextsin the first set of contexts and the second set of contexts aredifferent.

As another example, entropy decoding unit 302 may decode, utilizing afirst set of one or more contexts, the value for the BVD value for afirst block in a first picture, and decode, utilizing a second set ofone or more contexts, a motion vector difference (MVD) for a motionvector for a second block in a second picture. The motion vector for thesecond block identifies a block in a picture different than the secondpicture, and the MVD is indicative of a difference between the motionvector and a motion vector predictor. In one or more examples, one ormore contexts in the first set of contexts and the second set ofcontexts are different.

FIG. 4 is a flowchart illustrating an example method for encoding acurrent block in accordance with the techniques of this disclosure. Thecurrent block may comprise a current CU. Although described with respectto video encoder 200 (FIGS. 1 and 2 ), it should be understood thatother devices may be configured to perform a method similar to that ofFIG. 4 .

In this example, video encoder 200 initially predicts the current block(350). For example, video encoder 200 may form a prediction block forthe current block (e.g., based on a block vector for IBC). Video encoder200 may then calculate a residual block for the current block (352). Tocalculate the residual block, video encoder 200 may calculate adifference between the original, unencoded block and the predictionblock for the current block. Video encoder 200 may then transform theresidual block and quantize transform coefficients of the residual block(354). Next, video encoder 200 may scan the quantized transformcoefficients of the residual block (356). During the scan, or followingthe scan, video encoder 200 may entropy encode the transformcoefficients (358). For example, video encoder 200 may encode thetransform coefficients using CAVLC or CABAC. Video encoder 200 may thenoutput the entropy encoded data of the block (360).

FIG. 5 is a flowchart illustrating an example method for decoding acurrent block of video data in accordance with the techniques of thisdisclosure. The current block may comprise a current CU. Althoughdescribed with respect to video decoder 300 (FIGS. 1 and 3 ), it shouldbe understood that other devices may be configured to perform a methodsimilar to that of FIG. 5 .

Video decoder 300 may receive entropy encoded data for the currentblock, such as entropy encoded prediction information and entropyencoded data for transform coefficients of a residual blockcorresponding to the current block (370). Video decoder 300 may entropydecode the entropy encoded data to determine prediction information forthe current block and to reproduce transform coefficients of theresidual block (372). Video decoder 300 may predict the current block(374), e.g., using IBC mode as indicated by the prediction informationfor the current block, to calculate a prediction block for the currentblock. Video decoder 300 may then inverse scan the reproduced transformcoefficients (376), to create a block of quantized transformcoefficients. Video decoder 300 may then inverse quantize the transformcoefficients and apply an inverse transform to the transformcoefficients to produce a residual block (378). Video decoder 300 mayultimately decode the current block by combining the prediction blockand the residual block (380).

FIG. 7 is a flowchart illustrating an example method of encoding ordecoding video data in accordance with the techniques of thisdisclosure. Video encoder 200 and video decoder 300 may determine that ablock vector difference (BVD) value is non-zero (700). For instance,video encoder 200, based on rate-distortion calculations, may determinethat the optimal BVD is non-zero. Video decoder 300 may parse a firstflag indicating that the BVD value is non-zero. As described, the BVDvalue is indicative of a difference between a block vector for a currentblock of the video data and a block vector predictor, and the blockvector points to a reference block based on samples in a same picture asthe current block.

Video encoder 200 and video decoder 300 may encode or decode a value forthe BVD value, without signaling or parsing syntax informationindicating whether an absolute value of the BVD value is greater thanone (702). For example, video decoder 300 may decode the value withoutparsing a second flag indicating whether the absolute value of the BVDvalue is greater than one. The value (e.g., for the BVD value) may beequal to the absolute value of the BVD value minus one. In some

In some examples, the value is represented as a codeword (e.g., anExponential-Golomb codeword). In such examples, video encoder 200 andvideo decoder 300 may context-based encode or decode the codeword. As anexample, to context-based encode or decode the codeword, video encoder200 and video decoder 300 may context-based encode or decode a first Nbins of the codeword and bypass encode or decode the remaining bins ofthe codeword. As an example, the first N bins is the first 5 bins of thecodeword.

FIG. 8 is a flowchart illustrating an example method of encoding ordecoding components of a block vector difference (BVD). Video encoder200 and video decoder 300 may encode or decode, utilizing a first set ofone or more contexts, a horizontal component value for the BVD based onthe BVD horizontal component value being non-zero (800). Video encoder200 and video decoder 300 may encode or decode, utilizing a second setof one or more contexts, a vertical component value based on a BVDvertical component value being non-zero (802). In one or more examples,the one or more contexts in the first set of contexts and the second setof contexts are different.

FIG. 9 is a flowchart illustrating an example method of encoding ordecoding a BVD and a motion vector difference (MVD). Video encoder 200and video decoder 300 may encode or decode, utilizing a first set of oneor more contexts, a BVD value for a BVD for a block vector for a firstblock in a first picture (900). The BVD value is for a block vector forthe first block that points to a reference block in the first picture.Video encoder 200 and video decoder 300 may encode or decode, utilizinga second set of one or more contexts, a MVD value for a MVD for a motionvector for a second block in a second picture (902). The motion vectorfor the second block identifies a block in a picture different than thesecond picture, and the MVD is indicative of a difference between themotion vector and a motion vector predictor.

The following describes one or more example techniques in accordancewith examples described in this disclosure.

Clause 1. A method of coding video data, the method comprising: coding,utilizing a first set of one or more contexts, a motion vectordifference (MVD) for a motion vector for a first block in a firstpicture of the video data, wherein the motion vector for the first blockidentifies a block in a picture different than the first picture, andwherein the MVD is indicative of a difference between the motion vectorand a motion vector predictor; and coding, utilizing a second set of oneor more contexts, a block vector difference (BVD) for a block vector fora second block in a second picture of the video data, wherein the blockvector for the second block identifies a block in the second picture,and wherein the BVD is indicative of a difference between the blockvector and a block vector predictor, wherein one or more contexts in thefirst set of contexts and the second set of contexts are different.

Clause 2. A method of coding video data, the method comprising:determining whether a block vector difference (BVD) is zero or not,wherein the BVD is indicative of a difference between a block vector fora current block of the video data and a block vector predictor; andcontext-based coding the BVD based on the BVD being non-zero, withoutdetermining whether an absolute value of the BVD is one.

Clause 3. A method of coding video data, the method comprising:determining whether a block vector difference (BVD) is zero or not,wherein the BVD is indicative of a difference between a block vector fora current block of the video data and a block vector predictor; based onthe BVD being non-zero, determining whether the BVD is less than orequal to a threshold; selecting a binarization or inverse binarizationtechnique based on whether the BVD is less than or equal to a threshold;and applying the selected binarization or inverse binarizationtechnique.

Clause 4. A method of coding video data, the method comprising:context-coding, utilizing one or more contexts, a block vectordifference (BVD), wherein the BVD is indicative of a difference betweena block vector for a current block of the video data and a block vectorpredictor, wherein context-coding comprises utilizing the one or morecontexts for a part of a binarization codeword of the BVD or for thewhole binarization codeword of the BVD.

Clause 5. A method of coding video data, the method comprising:binarizing or inverse binarizing a horizontal component of a blockvector difference (BVD) utilizing a first binarization technique,wherein the BVD is indicative of a difference between a block vector fora current block of the video data and a block vector predictor; andbinarizing or inverse binarizing a vertical component of the BVDutilizing a second binarization technique that is different than thefirst binarization technique.

Clause 6. A method of coding video data, the method comprising:binarizing or inverse binarizing a horizontal and vertical component ofa block vector difference (BVD) utilizing the same binarizationtechnique, wherein the BVD is indicative of a difference between a blockvector for a current block of the video data and a block vectorpredictor; context-based coding the horizontal component; andcontext-based coding the horizontal component.

Clause 7. The method of clause 6, wherein context-based coding thehorizontal component and context-based coding the vertical componentcomprises context-based coding the vertical component and the horizontalcomponent utilizing the same contexts.

Clause 8. The method of clause 6, wherein context-based coding thehorizontal component and context-based coding the vertical componentcomprises context-based coding the vertical component and the horizontalcomponent utilizing different contexts.

Clause 9. The method of clause 6, wherein context-based coding thehorizontal component and context-based coding the vertical componentcomprises determining contexts for one of the horizontal component orthe vertical component based on the other of the horizontal component orthe vertical component.

Clause 10. A method of coding video data, the method comprising:determining a binarization or inverse binarization technique for a firstcomponent of a block vector difference (BVD) based on whether a secondcomponent of the BVD is positive or negative, wherein the BVD isindicative of a difference between a block vector for a current block ofthe video data and a block vector predictor, and wherein the firstcomponent is one of a horizontal or vertical component of the BVD, andthe second component is the other of the horizontal or verticalcomponent of the BVD; and applying the determined binarization orinverse binarization technique.

Clause 11. A method of coding video data, the method comprising:determining a binarization or inverse binarization technique for a firstcomponent of a block vector difference (BVD) based on a value of asecond component of the BVD, wherein the BVD is indicative of adifference between a block vector for a current block of the video dataand a block vector predictor, and wherein the first component is one ofa horizontal or vertical component of the BVD, and the second componentis the other of the horizontal or vertical component of the BVD; andapplying the determined binarization or inverse binarization technique.

Clause 12. A method of coding video data, the method comprising:determining a binarization or inverse binarization technique for a firstcomponent of a block vector difference (BVD) and a second component ofthe BVD based on whether the first component and the second componentare both positive, both negative, or one is positive and the other isnegative, and wherein the BVD is indicative of a difference between ablock vector for a current block of the video data and a block vectorpredictor, wherein the first component is one of a horizontal orvertical component of the BVD, and the second component is the other ofthe horizontal or vertical component of the BVD; and applying thedetermined binarization or inverse binarization technique.

Clause 13. The method of any of clauses 1-12, wherein the methodcomprising a method of decoding video data.

Clause 14. The method of any of clauses 1-12, wherein the methodcomprising a method of encoding video data.

Clause 15. A device for coding video data, the device comprising: memoryconfigured to store the video data; and processing circuitry configuredto perform the method of any one of clauses 1-14.

Clause 16. The device of clause 15, further comprising a displayconfigured to display decoded video data.

Clause 17. The device of any of clauses 15 and 16, wherein the devicecomprises one or more of a camera, a computer, a mobile device, abroadcast receiver device, or a set-top box.

Clause 18. The device of any of clauses 15-17, wherein the devicecomprises a video decoder.

Clause 19. The device of any of clauses 15-17, wherein the devicecomprises a video encoder.

Clause 20. A computer-readable storage medium having stored thereoninstructions that, when executed, cause one or more processors toperform the method of any of clauses 1-14.

Clause 21. A device for coding video data, the device comprising meansfor performing the method of any of clauses 1-14.

Clause 1A. A method of encoding or decoding video data, the methodcomprising: determining that a block vector difference (BVD) value isnon-zero, wherein the BVD value is indicative of a difference between ablock vector for a current block of the video data and a block vectorpredictor, and wherein the block vector points to a reference blockbased on samples in a same picture as the current block; and encoding ordecoding a value for the BVD value, without signaling or parsing syntaxinformation indicating whether an absolute value of the BVD value isgreater than one.

Clause 2A. The method of clause 1A, wherein the value is equal to theabsolute value of the BVD value minus one.

Clause 3A. The method of any of clauses 1A and 2A, wherein the value isrepresented as a codeword, wherein encoding or decoding the valuecomprises context-based encoding or decoding the codeword.

Clause 4A. The method of clause 3A, wherein context-based encoding ordecoding the codeword comprises context-based encoding or decoding afirst N bins of the codeword and bypass encoding or decoding remainingbins of the codeword.

Clause 5A. The method of clause 4A, wherein the first N bins comprisethe first 5 bins of the codeword.

Clause 6A. The method of any of clauses 3A-5A, wherein the codeword isan Exponential-Golomb codeword.

Clause 7A. The method of any of clauses 1A-6A, wherein determining thatthe BVD value is non-zero comprises parsing a first flag indicating thatthe BVD value is non-zero, and wherein encoding or decoding the valuebased on the BVD value being non-zero, without signaling or parsingsyntax information indicating whether the absolute value of the BVDvalue is greater than one comprises decoding the value without parsing asecond flag indicating whether the absolute value of the BVD value isgreater than one.

Clause 8A. The method of any of clauses 1A-7A, wherein the BVD value isa BVD horizontal component value, wherein the value is a horizontalcomponent value, and wherein encoding or decoding the value based on theBVD value being non-zero comprises encoding or decoding, utilizing afirst set of one or more contexts, the horizontal component value basedon the BVD horizontal component value being non-zero, the method furthercomprising encoding or decoding, utilizing a second set of one or morecontexts, a vertical component value based on a BVD vertical componentvalue being non-zero, wherein the one or more contexts in the first setof contexts and the second set of contexts are different.

Clause 9A. The method of any of clauses 1A-8A, wherein the picture thatincludes the current block comprises a first picture, wherein thecurrent block is a first block, and wherein encoding or decoding thevalue comprises encoding or decoding, utilizing a first set of one ormore contexts, the value, the method further comprising: encoding ordecoding, utilizing a second set of one or more contexts, a motionvector difference (MVD) for a motion vector for a second block in asecond picture, wherein the motion vector for the second blockidentifies a block in a picture different than the second picture, andwherein the MVD is indicative of a difference between the motion vectorand a motion vector predictor, wherein one or more contexts in the firstset of contexts and the second set of contexts are different.

Clause 10A. The method of any of clauses 1A-9A, wherein encoding ordecoding the value comprises decoding the value, the method furthercomprising: determining the block vector for the current block based onthe BVD value; determining a prediction block based on the block vector;receiving residual information indicative of a difference between theprediction block and the current block; and reconstructing the currentblock based on the residual information and the prediction block.

Clause 11A. A device for encoding or decoding video data, the devicecomprising: memory configured to store video data; and processingcircuitry configured to: determine that a block vector difference (BVD)value is non-zero, wherein the BVD value is indicative of a differencebetween a block vector for a current block of the video data and a blockvector predictor, and wherein the block vector points to a referenceblock based on samples in a same picture as the current block; andencode or decode a value for the BVD value, without signaling or parsingsyntax information indicating whether an absolute value of the BVD valueis greater than one.

Clause 12A. The device of clause 11A, wherein the value is equal to theabsolute value of the BVD value minus one.

Clause 13A. The device of any of clauses 11A and 12A, wherein the valueis represented as a codeword, wherein to encode or decode the value, theprocessing circuitry is configured to context-based encode or decode thecodeword.

Clause 14A. The device of clause 13A, wherein to context-based encode ordecode the codeword, the processing circuitry is configured tocontext-based encode or decode a first N bins of the codeword and bypassencode or decode remaining bins of the codeword.

Clause 15A. The device of clause 14A, wherein the first N bins comprisethe first 5 bins of the codeword.

Clause 16A. The device of any of clauses 13A-15A, wherein the codewordis an Exponential-Golomb codeword.

Clause 17A. The device of any of clauses 11A-16A, wherein to determinethat the BVD value is non-zero, the processing circuitry is configuredto parse a first flag indicating that the BVD value is non-zero, andwherein to encode or decode the value based on the BVD value beingnon-zero, without signaling or parsing syntax information indicatingwhether the absolute value of the BVD value is greater than one, theprocessing circuitry is configured to decode the value without parsing asecond flag indicating whether the absolute value of the BVD value isgreater than one.

Clause 18A. The device of any of clauses 11A-17A, wherein the BVD valueis a BVD horizontal component value, wherein the value is a horizontalcomponent value, and wherein to encode or decode the value based on theBVD value being non-zero, the processing circuitry is configured toencode or decode, utilizing a first set of one or more contexts, thehorizontal component value based on the BVD horizontal component valuebeing non-zero, wherein the processing circuitry is further configuredto encode or decode, utilizing a second set of one or more contexts, avertical component value based on a BVD vertical component value beingnon-zero, wherein the one or more contexts in the first set of contextsand the second set of contexts are different.

Clause 19A. The device of any of clauses 11A-18A, wherein the picturethat includes the current block comprises a first picture, wherein thecurrent block is a first block, and wherein to encode or decode thevalue, the processing circuitry is configured to encode or decode,utilizing a first set of one or more contexts, the value, wherein theprocessing circuitry is further configured to: encode or decode,utilizing a second set of one or more contexts, a motion vectordifference (MVD) for a motion vector for a second block in a secondpicture, wherein the motion vector for the second block identifies ablock in a picture different than the second picture, and wherein theMVD is indicative of a difference between the motion vector and a motionvector predictor, wherein one or more contexts in the first set ofcontexts and the second set of contexts are different.

Clause 20A. A computer-readable storage medium storing instructionsthereon that when executed cause one or more processors to: determinethat a block vector difference (BVD) value is non-zero, wherein the BVDvalue is indicative of a difference between a block vector for a currentblock of video data and a block vector predictor, and wherein the blockvector points to a reference block based on samples in a same picture asthe current block; and encode or decode a value for the BVD value,without signaling or parsing syntax information indicating whether anabsolute value of the BVD value is greater than one.

Clause 21A. The computer-readable storage medium of clause 20A, furthercomprising instructions that cause the one or more processors to performthe method of any of clauses 1A-10A.

Clause 22A. A device comprising means for performing the method of anyof clauses 1A-10A.

It is to be recognized that depending on the example, certain acts orevents of any of the techniques described herein can be performed in adifferent sequence, may be added, merged, or left out altogether (e.g.,not all described acts or events are necessary for the practice of thetechniques). Moreover, in certain examples, acts or events may beperformed concurrently, e.g., through multi-threaded processing,interrupt processing, or multiple processors, rather than sequentially.

In one or more examples, the functions described may be implemented inhardware, software, firmware, or any combination thereof. If implementedin software, the functions may be stored on or transmitted over as oneor more instructions or code on a computer-readable medium and executedby a hardware-based processing unit. Computer-readable media may includecomputer-readable storage media, which corresponds to a tangible mediumsuch as data storage media, or communication media including any mediumthat facilitates transfer of a computer program from one place toanother, e.g., according to a communication protocol. In this manner,computer-readable media generally may correspond to (1) tangiblecomputer-readable storage media which is non-transitory or (2) acommunication medium such as a signal or carrier wave. Data storagemedia may be any available media that can be accessed by one or morecomputers or one or more processors to retrieve instructions, codeand/or data structures for implementation of the techniques described inthis disclosure. A computer program product may include acomputer-readable medium.

By way of example, and not limitation, such computer-readable storagemedia can comprise RAM, ROM, EEPROM, CD-ROM or other optical diskstorage, magnetic disk storage, or other magnetic storage devices, flashmemory, or any other medium that can be used to store desired programcode in the form of instructions or data structures and that can beaccessed by a computer. Also, any connection is properly termed acomputer-readable medium. For example, if instructions are transmittedfrom a website, server, or other remote source using a coaxial cable,fiber optic cable, twisted pair, digital subscriber line (DSL), orwireless technologies such as infrared, radio, and microwave, then thecoaxial cable, fiber optic cable, twisted pair, DSL, or wirelesstechnologies such as infrared, radio, and microwave are included in thedefinition of medium. It should be understood, however, thatcomputer-readable storage media and data storage media do not includeconnections, carrier waves, signals, or other transitory media, but areinstead directed to non-transitory, tangible storage media. Disk anddisc, as used herein, includes compact disc (CD), laser disc, opticaldisc, digital versatile disc (DVD), floppy disk and Blu-ray disc, wheredisks usually reproduce data magnetically, while discs reproduce dataoptically with lasers. Combinations of the above should also be includedwithin the scope of computer-readable media.

Instructions may be executed by one or more processors, such as one ormore DSPs, general purpose microprocessors, ASICs, FPGAs, or otherequivalent integrated or discrete logic circuitry. Accordingly, theterms “processor” and “processing circuitry,” as used herein may referto any of the foregoing structures or any other structure suitable forimplementation of the techniques described herein. In addition, in someaspects, the functionality described herein may be provided withindedicated hardware and/or software modules configured for encoding anddecoding, or incorporated in a combined codec. Also, the techniquescould be fully implemented in one or more circuits or logic elements.

The techniques of this disclosure may be implemented in a wide varietyof devices or apparatuses, including a wireless handset, an integratedcircuit (IC) or a set of ICs (e.g., a chip set). Various components,modules, or units are described in this disclosure to emphasizefunctional aspects of devices configured to perform the disclosedtechniques, but do not necessarily require realization by differenthardware units. Rather, as described above, various units may becombined in a codec hardware unit or provided by a collection ofinteroperative hardware units, including one or more processors asdescribed above, in conjunction with suitable software and/or firmware.

Various examples have been described. These and other examples arewithin the scope of the following claims.

What is claimed is:
 1. A method of encoding or decoding video data, themethod comprising: determining that a block vector difference (BVD)value is non-zero, wherein the BVD value is indicative of a differencebetween a block vector for a current block of the video data and a blockvector predictor, and wherein the block vector points to a referenceblock based on samples in a same picture as the current block; andencoding or decoding a value for the BVD value, without signaling orparsing syntax information indicating whether an absolute value of theBVD value is greater than one.
 2. The method of claim 1, wherein thevalue is equal to the absolute value of the BVD value minus one.
 3. Themethod of claim 1, wherein the value is represented as a codeword,wherein encoding or decoding the value comprises context-based encodingor decoding the codeword.
 4. The method of claim 3, whereincontext-based encoding or decoding the codeword comprises context-basedencoding or decoding a first N bins of the codeword and bypass encodingor decoding remaining bins of the codeword.
 5. The method of claim 4,wherein the first N bins comprise the first 5 bins of the codeword. 6.The method of claim 3, wherein the codeword is an Exponential-Golombcodeword.
 7. The method of claim 1, wherein determining that the BVDvalue is non-zero comprises parsing a first flag indicating that the BVDvalue is non-zero, and wherein encoding or decoding the value based onthe BVD value being non-zero, without signaling or parsing syntaxinformation indicating whether the absolute value of the BVD value isgreater than one comprises decoding the value without parsing a secondflag indicating whether the absolute value of the BVD value is greaterthan one.
 8. The method of claim 1, wherein the BVD value is a BVDhorizontal component value, wherein the value is a horizontal componentvalue, and wherein encoding or decoding the value based on the BVD valuebeing non-zero comprises encoding or decoding, utilizing a first set ofone or more contexts, the horizontal component value based on the BVDhorizontal component value being non-zero, the method further comprisingencoding or decoding, utilizing a second set of one or more contexts, avertical component value based on a BVD vertical component value beingnon-zero, wherein the one or more contexts in the first set of contextsand the second set of contexts are different.
 9. The method of claim 1,wherein the picture that includes the current block comprises a firstpicture, wherein the current block is a first block, and whereinencoding or decoding the value comprises encoding or decoding, utilizinga first set of one or more contexts, the value, the method furthercomprising: encoding or decoding, utilizing a second set of one or morecontexts, a motion vector difference (MVD) for a motion vector for asecond block in a second picture, wherein the motion vector for thesecond block identifies a block in a picture different than the secondpicture, and wherein the MVD is indicative of a difference between themotion vector and a motion vector predictor, wherein one or morecontexts in the first set of contexts and the second set of contexts aredifferent.
 10. The method of claim 1, wherein encoding or decoding thevalue comprises decoding the value, the method further comprising:determining the block vector for the current block based on the BVDvalue; determining a prediction block based on the block vector;receiving residual information indicative of a difference between theprediction block and the current block; and reconstructing the currentblock based on the residual information and the prediction block.
 11. Adevice for encoding or decoding video data, the device comprising:memory configured to store video data; and processing circuitryconfigured to: determine that a block vector difference (BVD) value isnon-zero, wherein the BVD value is indicative of a difference between ablock vector for a current block of the video data and a block vectorpredictor, and wherein the block vector points to a reference blockbased on samples in a same picture as the current block; and encode ordecode a value for the BVD value, without signaling or parsing syntaxinformation indicating whether an absolute value of the BVD value isgreater than one.
 12. The device of claim 11, wherein the value is equalto the absolute value of the BVD value minus one.
 13. The device ofclaim 11, wherein the value is represented as a codeword, wherein toencode or decode the value, the processing circuitry is configured tocontext-based encode or decode the codeword.
 14. The device of claim 13,wherein to context-based encode or decode the codeword, the processingcircuitry is configured to context-based encode or decode a first N binsof the codeword and bypass encode or decode remaining bins of thecodeword.
 15. The device of claim 14, wherein the first N bins comprisethe first 5 bins of the codeword.
 16. The device of claim 13, whereinthe codeword is an Exponential-Golomb codeword.
 17. The device of claim11, wherein to determine that the BVD value is non-zero, the processingcircuitry is configured to parse a first flag indicating that the BVDvalue is non-zero, and wherein to encode or decode the value based onthe BVD value being non-zero, without signaling or parsing syntaxinformation indicating whether the absolute value of the BVD value isgreater than one, the processing circuitry is configured to decode thevalue without parsing a second flag indicating whether the absolutevalue of the BVD value is greater than one.
 18. The device of claim 11,wherein the BVD value is a BVD horizontal component value, wherein thevalue is a horizontal component value, and wherein to encode or decodethe value based on the BVD value being non-zero, the processingcircuitry is configured to encode or decode, utilizing a first set ofone or more contexts, the horizontal component value based on the BVDhorizontal component value being non-zero, wherein the processingcircuitry is further configured to encode or decode, utilizing a secondset of one or more contexts, a vertical component value based on a BVDvertical component value being non-zero, wherein the one or morecontexts in the first set of contexts and the second set of contexts aredifferent.
 19. The device of claim 11, wherein the picture that includesthe current block comprises a first picture, wherein the current blockis a first block, and wherein to encode or decode the value, theprocessing circuitry is configured to encode or decode, utilizing afirst set of one or more contexts, the value, wherein the processingcircuitry is further configured to: encode or decode, utilizing a secondset of one or more contexts, a motion vector difference (MVD) for amotion vector for a second block in a second picture, wherein the motionvector for the second block identifies a block in a picture differentthan the second picture, and wherein the MVD is indicative of adifference between the motion vector and a motion vector predictor,wherein one or more contexts in the first set of contexts and the secondset of contexts are different.
 20. A computer-readable storage mediumstoring instructions thereon that when executed cause one or moreprocessors to: determine that a block vector difference (BVD) value isnon-zero, wherein the BVD value is indicative of a difference between ablock vector for a current block of video data and a block vectorpredictor, and wherein the block vector points to a reference blockbased on samples in a same picture as the current block; and encode ordecode a value for the BVD value, without signaling or parsing syntaxinformation indicating whether an absolute value of the BVD value isgreater than one.